xref: /petsc/src/mat/impls/baij/seq/baij2.c (revision 9371c9d470a9602b6d10a8bf50c9b2280a79e45a)

#include <../src/mat/impls/baij/seq/baij.h>
#include <../src/mat/impls/dense/seq/dense.h>
#include <petsc/private/kernels/blockinvert.h>
#include <petscbt.h>
#include <petscblaslapack.h>

#if defined(PETSC_HAVE_IMMINTRIN_H) && defined(__AVX2__) && defined(__FMA__) && defined(PETSC_USE_REAL_DOUBLE) && !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_64BIT_INDICES)
#include <immintrin.h>
#endif

PetscErrorCode MatIncreaseOverlap_SeqBAIJ(Mat A, PetscInt is_max, IS is[], PetscInt ov) {
  Mat_SeqBAIJ    *a = (Mat_SeqBAIJ *)A->data;
  PetscInt        row, i, j, k, l, m, n, *nidx, isz, val, ival;
  const PetscInt *idx;
  PetscInt        start, end, *ai, *aj, bs, *nidx2;
  PetscBT         table;

  PetscFunctionBegin;
  m  = a->mbs;
  ai = a->i;
  aj = a->j;
  bs = A->rmap->bs;

  PetscCheck(ov >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Negative overlap specified");

  PetscCall(PetscBTCreate(m, &table));
  PetscCall(PetscMalloc1(m + 1, &nidx));
  PetscCall(PetscMalloc1(A->rmap->N + 1, &nidx2));

  for (i = 0; i < is_max; i++) {
    /* Initialise the two local arrays */
    isz = 0;
    PetscCall(PetscBTMemzero(m, table));

    /* Extract the indices, assume there can be duplicate entries */
    PetscCall(ISGetIndices(is[i], &idx));
    PetscCall(ISGetLocalSize(is[i], &n));

    /* Enter these into the temp arrays i.e mark table[row], enter row into new index */
    for (j = 0; j < n; ++j) {
      ival = idx[j] / bs; /* convert the indices into block indices */
      PetscCheck(ival < m, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "index greater than mat-dim");
      if (!PetscBTLookupSet(table, ival)) nidx[isz++] = ival;
    }
    PetscCall(ISRestoreIndices(is[i], &idx));
    PetscCall(ISDestroy(&is[i]));

    k = 0;
    for (j = 0; j < ov; j++) { /* for each overlap*/
      n = isz;
      for (; k < n; k++) { /* do only those rows in nidx[k], which are not done yet */
        row   = nidx[k];
        start = ai[row];
        end   = ai[row + 1];
        for (l = start; l < end; l++) {
          val = aj[l];
          if (!PetscBTLookupSet(table, val)) nidx[isz++] = val;
        }
      }
    }
    /* expand the Index Set */
    for (j = 0; j < isz; j++) {
      for (k = 0; k < bs; k++) nidx2[j * bs + k] = nidx[j] * bs + k;
    }
    PetscCall(ISCreateGeneral(PETSC_COMM_SELF, isz * bs, nidx2, PETSC_COPY_VALUES, is + i));
  }
  PetscCall(PetscBTDestroy(&table));
  PetscCall(PetscFree(nidx));
  PetscCall(PetscFree(nidx2));
  PetscFunctionReturn(0);
}

PetscErrorCode MatCreateSubMatrix_SeqBAIJ_Private(Mat A, IS isrow, IS iscol, MatReuse scall, Mat *B) {
  Mat_SeqBAIJ    *a = (Mat_SeqBAIJ *)A->data, *c;
  PetscInt       *smap, i, k, kstart, kend, oldcols = a->nbs, *lens;
  PetscInt        row, mat_i, *mat_j, tcol, *mat_ilen;
  const PetscInt *irow, *icol;
  PetscInt        nrows, ncols, *ssmap, bs = A->rmap->bs, bs2 = a->bs2;
  PetscInt       *aj = a->j, *ai = a->i;
  MatScalar      *mat_a;
  Mat             C;
  PetscBool       flag;

  PetscFunctionBegin;
  PetscCall(ISGetIndices(isrow, &irow));
  PetscCall(ISGetIndices(iscol, &icol));
  PetscCall(ISGetLocalSize(isrow, &nrows));
  PetscCall(ISGetLocalSize(iscol, &ncols));

  PetscCall(PetscCalloc1(1 + oldcols, &smap));
  ssmap = smap;
  PetscCall(PetscMalloc1(1 + nrows, &lens));
  for (i = 0; i < ncols; i++) smap[icol[i]] = i + 1;
  /* determine lens of each row */
  for (i = 0; i < nrows; i++) {
    kstart  = ai[irow[i]];
    kend    = kstart + a->ilen[irow[i]];
    lens[i] = 0;
    for (k = kstart; k < kend; k++) {
      if (ssmap[aj[k]]) lens[i]++;
    }
  }
  /* Create and fill new matrix */
  if (scall == MAT_REUSE_MATRIX) {
    c = (Mat_SeqBAIJ *)((*B)->data);

    PetscCheck(c->mbs == nrows && c->nbs == ncols && (*B)->rmap->bs == bs, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Submatrix wrong size");
    PetscCall(PetscArraycmp(c->ilen, lens, c->mbs, &flag));
    PetscCheck(flag, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Cannot reuse matrix. wrong no of nonzeros");
    PetscCall(PetscArrayzero(c->ilen, c->mbs));
    C = *B;
  } else {
    PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &C));
    PetscCall(MatSetSizes(C, nrows * bs, ncols * bs, PETSC_DETERMINE, PETSC_DETERMINE));
    PetscCall(MatSetType(C, ((PetscObject)A)->type_name));
    PetscCall(MatSeqBAIJSetPreallocation(C, bs, 0, lens));
  }
  c = (Mat_SeqBAIJ *)(C->data);
  for (i = 0; i < nrows; i++) {
    row      = irow[i];
    kstart   = ai[row];
    kend     = kstart + a->ilen[row];
    mat_i    = c->i[i];
    mat_j    = c->j ? c->j + mat_i : NULL;       /* mustn't add to NULL, that is UB */
    mat_a    = c->a ? c->a + mat_i * bs2 : NULL; /* mustn't add to NULL, that is UB */
    mat_ilen = c->ilen + i;
    for (k = kstart; k < kend; k++) {
      if ((tcol = ssmap[a->j[k]])) {
        *mat_j++ = tcol - 1;
        PetscCall(PetscArraycpy(mat_a, a->a + k * bs2, bs2));
        mat_a += bs2;
        (*mat_ilen)++;
      }
    }
  }
  /* sort */
  if (c->j && c->a) {
    MatScalar *work;
    PetscCall(PetscMalloc1(bs2, &work));
    for (i = 0; i < nrows; i++) {
      PetscInt ilen;
      mat_i = c->i[i];
      mat_j = c->j + mat_i;
      mat_a = c->a + mat_i * bs2;
      ilen  = c->ilen[i];
      PetscCall(PetscSortIntWithDataArray(ilen, mat_j, mat_a, bs2 * sizeof(MatScalar), work));
    }
    PetscCall(PetscFree(work));
  }

  /* Free work space */
  PetscCall(ISRestoreIndices(iscol, &icol));
  PetscCall(PetscFree(smap));
  PetscCall(PetscFree(lens));
  PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
  PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));

  PetscCall(ISRestoreIndices(isrow, &irow));
  *B = C;
  PetscFunctionReturn(0);
}

PetscErrorCode MatCreateSubMatrix_SeqBAIJ(Mat A, IS isrow, IS iscol, MatReuse scall, Mat *B) {
  Mat_SeqBAIJ    *a = (Mat_SeqBAIJ *)A->data;
  IS              is1, is2;
  PetscInt       *vary, *iary, nrows, ncols, i, bs = A->rmap->bs, count, maxmnbs, j;
  const PetscInt *irow, *icol;

  PetscFunctionBegin;
  PetscCall(ISGetIndices(isrow, &irow));
  PetscCall(ISGetIndices(iscol, &icol));
  PetscCall(ISGetLocalSize(isrow, &nrows));
  PetscCall(ISGetLocalSize(iscol, &ncols));

  /* Verify if the indices corespond to each element in a block
   and form the IS with compressed IS */
  maxmnbs = PetscMax(a->mbs, a->nbs);
  PetscCall(PetscMalloc2(maxmnbs, &vary, maxmnbs, &iary));
  PetscCall(PetscArrayzero(vary, a->mbs));
  for (i = 0; i < nrows; i++) vary[irow[i] / bs]++;
  for (i = 0; i < a->mbs; i++) { PetscCheck(vary[i] == 0 || vary[i] == bs, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Index set does not match blocks"); }
  count = 0;
  for (i = 0; i < nrows; i++) {
    j = irow[i] / bs;
    if ((vary[j]--) == bs) iary[count++] = j;
  }
  PetscCall(ISCreateGeneral(PETSC_COMM_SELF, count, iary, PETSC_COPY_VALUES, &is1));

  PetscCall(PetscArrayzero(vary, a->nbs));
  for (i = 0; i < ncols; i++) vary[icol[i] / bs]++;
  for (i = 0; i < a->nbs; i++) { PetscCheck(vary[i] == 0 || vary[i] == bs, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Internal error in PETSc"); }
  count = 0;
  for (i = 0; i < ncols; i++) {
    j = icol[i] / bs;
    if ((vary[j]--) == bs) iary[count++] = j;
  }
  PetscCall(ISCreateGeneral(PETSC_COMM_SELF, count, iary, PETSC_COPY_VALUES, &is2));
  PetscCall(ISRestoreIndices(isrow, &irow));
  PetscCall(ISRestoreIndices(iscol, &icol));
  PetscCall(PetscFree2(vary, iary));

  PetscCall(MatCreateSubMatrix_SeqBAIJ_Private(A, is1, is2, scall, B));
  PetscCall(ISDestroy(&is1));
  PetscCall(ISDestroy(&is2));
  PetscFunctionReturn(0);
}

PetscErrorCode MatDestroySubMatrix_SeqBAIJ(Mat C) {
  Mat_SeqBAIJ *c       = (Mat_SeqBAIJ *)C->data;
  Mat_SubSppt *submatj = c->submatis1;

  PetscFunctionBegin;
  PetscCall((*submatj->destroy)(C));
  PetscCall(MatDestroySubMatrix_Private(submatj));
  PetscFunctionReturn(0);
}

/* Note this has code duplication with MatDestroySubMatrices_SeqAIJ() */
PetscErrorCode MatDestroySubMatrices_SeqBAIJ(PetscInt n, Mat *mat[]) {
  PetscInt     i;
  Mat          C;
  Mat_SeqBAIJ *c;
  Mat_SubSppt *submatj;

  PetscFunctionBegin;
  for (i = 0; i < n; i++) {
    C       = (*mat)[i];
    c       = (Mat_SeqBAIJ *)C->data;
    submatj = c->submatis1;
    if (submatj) {
      if (--((PetscObject)C)->refct <= 0) {
        PetscCall(PetscFree(C->factorprefix));
        PetscCall((*submatj->destroy)(C));
        PetscCall(MatDestroySubMatrix_Private(submatj));
        PetscCall(PetscFree(C->defaultvectype));
        PetscCall(PetscLayoutDestroy(&C->rmap));
        PetscCall(PetscLayoutDestroy(&C->cmap));
        PetscCall(PetscHeaderDestroy(&C));
      }
    } else {
      PetscCall(MatDestroy(&C));
    }
  }

  /* Destroy Dummy submatrices created for reuse */
  PetscCall(MatDestroySubMatrices_Dummy(n, mat));

  PetscCall(PetscFree(*mat));
  PetscFunctionReturn(0);
}

PetscErrorCode MatCreateSubMatrices_SeqBAIJ(Mat A, PetscInt n, const IS irow[], const IS icol[], MatReuse scall, Mat *B[]) {
  PetscInt i;

  PetscFunctionBegin;
  if (scall == MAT_INITIAL_MATRIX) { PetscCall(PetscCalloc1(n + 1, B)); }

  for (i = 0; i < n; i++) { PetscCall(MatCreateSubMatrix_SeqBAIJ(A, irow[i], icol[i], scall, &(*B)[i])); }
  PetscFunctionReturn(0);
}

/* -------------------------------------------------------*/
/* Should check that shapes of vectors and matrices match */
/* -------------------------------------------------------*/

PetscErrorCode MatMult_SeqBAIJ_1(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z, sum;
  const PetscScalar *x;
  const MatScalar   *v;
  PetscInt           mbs, i, n;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &z));

  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(z, a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
  }

  for (i = 0; i < mbs; i++) {
    n   = ii[1] - ii[0];
    v   = a->a + ii[0];
    idx = a->j + ii[0];
    ii++;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);       /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 1 * n, 1 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    sum = 0.0;
    PetscSparseDensePlusDot(sum, x, v, idx, n);
    if (usecprow) {
      z[ridx[i]] = sum;
    } else {
      z[i] = sum;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &z));
  PetscCall(PetscLogFlops(2.0 * a->nz - a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMult_SeqBAIJ_2(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, *zarray;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2;
  const MatScalar   *v;
  PetscInt           mbs, i, *idx, *ii, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 2 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    sum1 = 0.0;
    sum2 = 0.0;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);       /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 4 * n, 4 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 2 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      sum1 += v[0] * x1 + v[2] * x2;
      sum2 += v[1] * x1 + v[3] * x2;
      v += 4;
    }
    if (usecprow) z = zarray + 2 * ridx[i];
    z[0] = sum1;
    z[1] = sum2;
    if (!usecprow) z += 2;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(8.0 * a->nz - 2.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMult_SeqBAIJ_3(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, x1, x2, x3, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs, i, *idx, *ii, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

#if defined(PETSC_HAVE_PRAGMA_DISJOINT)
#pragma disjoint(*v, *z, *xb)
#endif

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 3 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    sum1 = 0.0;
    sum2 = 0.0;
    sum3 = 0.0;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);       /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 9 * n, 9 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 3 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];

      sum1 += v[0] * x1 + v[3] * x2 + v[6] * x3;
      sum2 += v[1] * x1 + v[4] * x2 + v[7] * x3;
      sum3 += v[2] * x1 + v[5] * x2 + v[8] * x3;
      v += 9;
    }
    if (usecprow) z = zarray + 3 * ridx[i];
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    if (!usecprow) z += 3;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(18.0 * a->nz - 3.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMult_SeqBAIJ_4(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, x1, x2, x3, x4, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs, i, *idx, *ii, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 4 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    sum1 = 0.0;
    sum2 = 0.0;
    sum3 = 0.0;
    sum4 = 0.0;

    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 16 * n, 16 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 4 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      sum1 += v[0] * x1 + v[4] * x2 + v[8] * x3 + v[12] * x4;
      sum2 += v[1] * x1 + v[5] * x2 + v[9] * x3 + v[13] * x4;
      sum3 += v[2] * x1 + v[6] * x2 + v[10] * x3 + v[14] * x4;
      sum4 += v[3] * x1 + v[7] * x2 + v[11] * x3 + v[15] * x4;
      v += 16;
    }
    if (usecprow) z = zarray + 4 * ridx[i];
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    if (!usecprow) z += 4;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(32.0 * a->nz - 4.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMult_SeqBAIJ_5(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, x1, x2, x3, x4, x5, *zarray;
  const PetscScalar *xb, *x;
  const MatScalar   *v;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscInt           mbs, i, j, n;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 5 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    sum1 = 0.0;
    sum2 = 0.0;
    sum3 = 0.0;
    sum4 = 0.0;
    sum5 = 0.0;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 25 * n, 25 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 5 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      sum1 += v[0] * x1 + v[5] * x2 + v[10] * x3 + v[15] * x4 + v[20] * x5;
      sum2 += v[1] * x1 + v[6] * x2 + v[11] * x3 + v[16] * x4 + v[21] * x5;
      sum3 += v[2] * x1 + v[7] * x2 + v[12] * x3 + v[17] * x4 + v[22] * x5;
      sum4 += v[3] * x1 + v[8] * x2 + v[13] * x3 + v[18] * x4 + v[23] * x5;
      sum5 += v[4] * x1 + v[9] * x2 + v[14] * x3 + v[19] * x4 + v[24] * x5;
      v += 25;
    }
    if (usecprow) z = zarray + 5 * ridx[i];
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    z[4] = sum5;
    if (!usecprow) z += 5;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(50.0 * a->nz - 5.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMult_SeqBAIJ_6(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, x5, x6, *zarray;
  const MatScalar   *v;
  PetscInt           mbs, i, *idx, *ii, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 6 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    sum1 = 0.0;
    sum2 = 0.0;
    sum3 = 0.0;
    sum4 = 0.0;
    sum5 = 0.0;
    sum6 = 0.0;

    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 36 * n, 36 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 6 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      x6 = xb[5];
      sum1 += v[0] * x1 + v[6] * x2 + v[12] * x3 + v[18] * x4 + v[24] * x5 + v[30] * x6;
      sum2 += v[1] * x1 + v[7] * x2 + v[13] * x3 + v[19] * x4 + v[25] * x5 + v[31] * x6;
      sum3 += v[2] * x1 + v[8] * x2 + v[14] * x3 + v[20] * x4 + v[26] * x5 + v[32] * x6;
      sum4 += v[3] * x1 + v[9] * x2 + v[15] * x3 + v[21] * x4 + v[27] * x5 + v[33] * x6;
      sum5 += v[4] * x1 + v[10] * x2 + v[16] * x3 + v[22] * x4 + v[28] * x5 + v[34] * x6;
      sum6 += v[5] * x1 + v[11] * x2 + v[17] * x3 + v[23] * x4 + v[29] * x5 + v[35] * x6;
      v += 36;
    }
    if (usecprow) z = zarray + 6 * ridx[i];
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    z[4] = sum5;
    z[5] = sum6;
    if (!usecprow) z += 6;
  }

  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(72.0 * a->nz - 6.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMult_SeqBAIJ_7(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, x5, x6, x7, *zarray;
  const MatScalar   *v;
  PetscInt           mbs, i, *idx, *ii, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 7 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    sum1 = 0.0;
    sum2 = 0.0;
    sum3 = 0.0;
    sum4 = 0.0;
    sum5 = 0.0;
    sum6 = 0.0;
    sum7 = 0.0;

    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 49 * n, 49 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 7 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      x6 = xb[5];
      x7 = xb[6];
      sum1 += v[0] * x1 + v[7] * x2 + v[14] * x3 + v[21] * x4 + v[28] * x5 + v[35] * x6 + v[42] * x7;
      sum2 += v[1] * x1 + v[8] * x2 + v[15] * x3 + v[22] * x4 + v[29] * x5 + v[36] * x6 + v[43] * x7;
      sum3 += v[2] * x1 + v[9] * x2 + v[16] * x3 + v[23] * x4 + v[30] * x5 + v[37] * x6 + v[44] * x7;
      sum4 += v[3] * x1 + v[10] * x2 + v[17] * x3 + v[24] * x4 + v[31] * x5 + v[38] * x6 + v[45] * x7;
      sum5 += v[4] * x1 + v[11] * x2 + v[18] * x3 + v[25] * x4 + v[32] * x5 + v[39] * x6 + v[46] * x7;
      sum6 += v[5] * x1 + v[12] * x2 + v[19] * x3 + v[26] * x4 + v[33] * x5 + v[40] * x6 + v[47] * x7;
      sum7 += v[6] * x1 + v[13] * x2 + v[20] * x3 + v[27] * x4 + v[34] * x5 + v[41] * x6 + v[48] * x7;
      v += 49;
    }
    if (usecprow) z = zarray + 7 * ridx[i];
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    z[4] = sum5;
    z[5] = sum6;
    z[6] = sum7;
    if (!usecprow) z += 7;
  }

  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(98.0 * a->nz - 7.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

#if defined(PETSC_HAVE_IMMINTRIN_H) && defined(__AVX2__) && defined(__FMA__) && defined(PETSC_USE_REAL_DOUBLE) && !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_64BIT_INDICES)
PetscErrorCode MatMult_SeqBAIJ_9_AVX2(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, *work, *workt, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs, i, bs = A->rmap->bs, j, n, bs2 = a->bs2;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscInt           k;
  PetscBool          usecprow = a->compressedrow.use;

  __m256d a0, a1, a2, a3, a4, a5;
  __m256d w0, w1, w2, w3;
  __m256d z0, z1, z2;
  __m256i mask1 = _mm256_set_epi64x(0LL, 0LL, 0LL, 1LL << 63);

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, bs * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  if (!a->mult_work) {
    k = PetscMax(A->rmap->n, A->cmap->n);
    PetscCall(PetscMalloc1(k + 1, &a->mult_work));
  }

  work = a->mult_work;
  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    workt = work;
    for (j = 0; j < n; j++) {
      xb = x + bs * (*idx++);
      for (k = 0; k < bs; k++) workt[k] = xb[k];
      workt += bs;
    }
    if (usecprow) z = zarray + bs * ridx[i];

    z0 = _mm256_setzero_pd();
    z1 = _mm256_setzero_pd();
    z2 = _mm256_setzero_pd();

    for (j = 0; j < n; j++) {
      /* first column of a */
      w0 = _mm256_set1_pd(work[j * 9]);
      a0 = _mm256_loadu_pd(&v[j * 81]);
      z0 = _mm256_fmadd_pd(a0, w0, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 4]);
      z1 = _mm256_fmadd_pd(a1, w0, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 8]);
      z2 = _mm256_fmadd_pd(a2, w0, z2);

      /* second column of a */
      w1 = _mm256_set1_pd(work[j * 9 + 1]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 9]);
      z0 = _mm256_fmadd_pd(a0, w1, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 13]);
      z1 = _mm256_fmadd_pd(a1, w1, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 17]);
      z2 = _mm256_fmadd_pd(a2, w1, z2);

      /* third column of a */
      w2 = _mm256_set1_pd(work[j * 9 + 2]);
      a3 = _mm256_loadu_pd(&v[j * 81 + 18]);
      z0 = _mm256_fmadd_pd(a3, w2, z0);
      a4 = _mm256_loadu_pd(&v[j * 81 + 22]);
      z1 = _mm256_fmadd_pd(a4, w2, z1);
      a5 = _mm256_loadu_pd(&v[j * 81 + 26]);
      z2 = _mm256_fmadd_pd(a5, w2, z2);

      /* fourth column of a */
      w3 = _mm256_set1_pd(work[j * 9 + 3]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 27]);
      z0 = _mm256_fmadd_pd(a0, w3, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 31]);
      z1 = _mm256_fmadd_pd(a1, w3, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 35]);
      z2 = _mm256_fmadd_pd(a2, w3, z2);

      /* fifth column of a */
      w0 = _mm256_set1_pd(work[j * 9 + 4]);
      a3 = _mm256_loadu_pd(&v[j * 81 + 36]);
      z0 = _mm256_fmadd_pd(a3, w0, z0);
      a4 = _mm256_loadu_pd(&v[j * 81 + 40]);
      z1 = _mm256_fmadd_pd(a4, w0, z1);
      a5 = _mm256_loadu_pd(&v[j * 81 + 44]);
      z2 = _mm256_fmadd_pd(a5, w0, z2);

      /* sixth column of a */
      w1 = _mm256_set1_pd(work[j * 9 + 5]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 45]);
      z0 = _mm256_fmadd_pd(a0, w1, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 49]);
      z1 = _mm256_fmadd_pd(a1, w1, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 53]);
      z2 = _mm256_fmadd_pd(a2, w1, z2);

      /* seventh column of a */
      w2 = _mm256_set1_pd(work[j * 9 + 6]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 54]);
      z0 = _mm256_fmadd_pd(a0, w2, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 58]);
      z1 = _mm256_fmadd_pd(a1, w2, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 62]);
      z2 = _mm256_fmadd_pd(a2, w2, z2);

      /* eighth column of a */
      w3 = _mm256_set1_pd(work[j * 9 + 7]);
      a3 = _mm256_loadu_pd(&v[j * 81 + 63]);
      z0 = _mm256_fmadd_pd(a3, w3, z0);
      a4 = _mm256_loadu_pd(&v[j * 81 + 67]);
      z1 = _mm256_fmadd_pd(a4, w3, z1);
      a5 = _mm256_loadu_pd(&v[j * 81 + 71]);
      z2 = _mm256_fmadd_pd(a5, w3, z2);

      /* ninth column of a */
      w0 = _mm256_set1_pd(work[j * 9 + 8]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 72]);
      z0 = _mm256_fmadd_pd(a0, w0, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 76]);
      z1 = _mm256_fmadd_pd(a1, w0, z1);
      a2 = _mm256_maskload_pd(&v[j * 81 + 80], mask1);
      z2 = _mm256_fmadd_pd(a2, w0, z2);
    }

    _mm256_storeu_pd(&z[0], z0);
    _mm256_storeu_pd(&z[4], z1);
    _mm256_maskstore_pd(&z[8], mask1, z2);

    v += n * bs2;
    if (!usecprow) z += bs;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(2.0 * a->nz * bs2 - bs * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}
#endif

PetscErrorCode MatMult_SeqBAIJ_11(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11;
  const PetscScalar *x, *xb;
  PetscScalar       *zarray, xv;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx;
  PetscInt           mbs, i, j, k, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  v = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 11 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n     = ii[i + 1] - ii[i];
    idx   = ij + ii[i];
    sum1  = 0.0;
    sum2  = 0.0;
    sum3  = 0.0;
    sum4  = 0.0;
    sum5  = 0.0;
    sum6  = 0.0;
    sum7  = 0.0;
    sum8  = 0.0;
    sum9  = 0.0;
    sum10 = 0.0;
    sum11 = 0.0;

    for (j = 0; j < n; j++) {
      xb = x + 11 * (idx[j]);

      for (k = 0; k < 11; k++) {
        xv = xb[k];
        sum1 += v[0] * xv;
        sum2 += v[1] * xv;
        sum3 += v[2] * xv;
        sum4 += v[3] * xv;
        sum5 += v[4] * xv;
        sum6 += v[5] * xv;
        sum7 += v[6] * xv;
        sum8 += v[7] * xv;
        sum9 += v[8] * xv;
        sum10 += v[9] * xv;
        sum11 += v[10] * xv;
        v += 11;
      }
    }
    if (usecprow) z = zarray + 11 * ridx[i];
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;

    if (!usecprow) z += 11;
  }

  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(242.0 * a->nz - 11.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

/* MatMult_SeqBAIJ_12 version 1: Columns in the block are accessed one at a time */
PetscErrorCode MatMult_SeqBAIJ_12_ver1(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12;
  const PetscScalar *x, *xb;
  PetscScalar       *zarray, xv;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx;
  PetscInt           mbs, i, j, k, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  v = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 12 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n     = ii[i + 1] - ii[i];
    idx   = ij + ii[i];
    sum1  = 0.0;
    sum2  = 0.0;
    sum3  = 0.0;
    sum4  = 0.0;
    sum5  = 0.0;
    sum6  = 0.0;
    sum7  = 0.0;
    sum8  = 0.0;
    sum9  = 0.0;
    sum10 = 0.0;
    sum11 = 0.0;
    sum12 = 0.0;

    for (j = 0; j < n; j++) {
      xb = x + 12 * (idx[j]);

      for (k = 0; k < 12; k++) {
        xv = xb[k];
        sum1 += v[0] * xv;
        sum2 += v[1] * xv;
        sum3 += v[2] * xv;
        sum4 += v[3] * xv;
        sum5 += v[4] * xv;
        sum6 += v[5] * xv;
        sum7 += v[6] * xv;
        sum8 += v[7] * xv;
        sum9 += v[8] * xv;
        sum10 += v[9] * xv;
        sum11 += v[10] * xv;
        sum12 += v[11] * xv;
        v += 12;
      }
    }
    if (usecprow) z = zarray + 12 * ridx[i];
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    if (!usecprow) z += 12;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(288.0 * a->nz - 12.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_12_ver1(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, *y = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12;
  const PetscScalar *x, *xb;
  PetscScalar       *zarray, *yarray, xv;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx;
  PetscInt           mbs = a->mbs, i, j, k, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  v = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 12 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n   = ii[i + 1] - ii[i];
    idx = ij + ii[i];

    if (usecprow) {
      y = yarray + 12 * ridx[i];
      z = zarray + 12 * ridx[i];
    }
    sum1  = y[0];
    sum2  = y[1];
    sum3  = y[2];
    sum4  = y[3];
    sum5  = y[4];
    sum6  = y[5];
    sum7  = y[6];
    sum8  = y[7];
    sum9  = y[8];
    sum10 = y[9];
    sum11 = y[10];
    sum12 = y[11];

    for (j = 0; j < n; j++) {
      xb = x + 12 * (idx[j]);

      for (k = 0; k < 12; k++) {
        xv = xb[k];
        sum1 += v[0] * xv;
        sum2 += v[1] * xv;
        sum3 += v[2] * xv;
        sum4 += v[3] * xv;
        sum5 += v[4] * xv;
        sum6 += v[5] * xv;
        sum7 += v[6] * xv;
        sum8 += v[7] * xv;
        sum9 += v[8] * xv;
        sum10 += v[9] * xv;
        sum11 += v[10] * xv;
        sum12 += v[11] * xv;
        v += 12;
      }
    }

    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    if (!usecprow) {
      y += 12;
      z += 12;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(288.0 * a->nz - 12.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

/* MatMult_SeqBAIJ_12_ver2 : Columns in the block are accessed in sets of 4,4,4 */
PetscErrorCode MatMult_SeqBAIJ_12_ver2(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, *zarray;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx, *ridx = NULL;
  PetscInt           mbs, i, j, n;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  v = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 12 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n   = ii[i + 1] - ii[i];
    idx = ij + ii[i];

    sum1 = sum2 = sum3 = sum4 = sum5 = sum6 = sum7 = sum8 = sum9 = sum10 = sum11 = sum12 = 0;
    for (j = 0; j < n; j++) {
      xb = x + 12 * (idx[j]);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];

      sum1 += v[0] * x1 + v[12] * x2 + v[24] * x3 + v[36] * x4;
      sum2 += v[1] * x1 + v[13] * x2 + v[25] * x3 + v[37] * x4;
      sum3 += v[2] * x1 + v[14] * x2 + v[26] * x3 + v[38] * x4;
      sum4 += v[3] * x1 + v[15] * x2 + v[27] * x3 + v[39] * x4;
      sum5 += v[4] * x1 + v[16] * x2 + v[28] * x3 + v[40] * x4;
      sum6 += v[5] * x1 + v[17] * x2 + v[29] * x3 + v[41] * x4;
      sum7 += v[6] * x1 + v[18] * x2 + v[30] * x3 + v[42] * x4;
      sum8 += v[7] * x1 + v[19] * x2 + v[31] * x3 + v[43] * x4;
      sum9 += v[8] * x1 + v[20] * x2 + v[32] * x3 + v[44] * x4;
      sum10 += v[9] * x1 + v[21] * x2 + v[33] * x3 + v[45] * x4;
      sum11 += v[10] * x1 + v[22] * x2 + v[34] * x3 + v[46] * x4;
      sum12 += v[11] * x1 + v[23] * x2 + v[35] * x3 + v[47] * x4;
      v += 48;

      x1 = xb[4];
      x2 = xb[5];
      x3 = xb[6];
      x4 = xb[7];

      sum1 += v[0] * x1 + v[12] * x2 + v[24] * x3 + v[36] * x4;
      sum2 += v[1] * x1 + v[13] * x2 + v[25] * x3 + v[37] * x4;
      sum3 += v[2] * x1 + v[14] * x2 + v[26] * x3 + v[38] * x4;
      sum4 += v[3] * x1 + v[15] * x2 + v[27] * x3 + v[39] * x4;
      sum5 += v[4] * x1 + v[16] * x2 + v[28] * x3 + v[40] * x4;
      sum6 += v[5] * x1 + v[17] * x2 + v[29] * x3 + v[41] * x4;
      sum7 += v[6] * x1 + v[18] * x2 + v[30] * x3 + v[42] * x4;
      sum8 += v[7] * x1 + v[19] * x2 + v[31] * x3 + v[43] * x4;
      sum9 += v[8] * x1 + v[20] * x2 + v[32] * x3 + v[44] * x4;
      sum10 += v[9] * x1 + v[21] * x2 + v[33] * x3 + v[45] * x4;
      sum11 += v[10] * x1 + v[22] * x2 + v[34] * x3 + v[46] * x4;
      sum12 += v[11] * x1 + v[23] * x2 + v[35] * x3 + v[47] * x4;
      v += 48;

      x1 = xb[8];
      x2 = xb[9];
      x3 = xb[10];
      x4 = xb[11];
      sum1 += v[0] * x1 + v[12] * x2 + v[24] * x3 + v[36] * x4;
      sum2 += v[1] * x1 + v[13] * x2 + v[25] * x3 + v[37] * x4;
      sum3 += v[2] * x1 + v[14] * x2 + v[26] * x3 + v[38] * x4;
      sum4 += v[3] * x1 + v[15] * x2 + v[27] * x3 + v[39] * x4;
      sum5 += v[4] * x1 + v[16] * x2 + v[28] * x3 + v[40] * x4;
      sum6 += v[5] * x1 + v[17] * x2 + v[29] * x3 + v[41] * x4;
      sum7 += v[6] * x1 + v[18] * x2 + v[30] * x3 + v[42] * x4;
      sum8 += v[7] * x1 + v[19] * x2 + v[31] * x3 + v[43] * x4;
      sum9 += v[8] * x1 + v[20] * x2 + v[32] * x3 + v[44] * x4;
      sum10 += v[9] * x1 + v[21] * x2 + v[33] * x3 + v[45] * x4;
      sum11 += v[10] * x1 + v[22] * x2 + v[34] * x3 + v[46] * x4;
      sum12 += v[11] * x1 + v[23] * x2 + v[35] * x3 + v[47] * x4;
      v += 48;
    }
    if (usecprow) z = zarray + 12 * ridx[i];
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    if (!usecprow) z += 12;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(288.0 * a->nz - 12.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

/* MatMultAdd_SeqBAIJ_12_ver2 : Columns in the block are accessed in sets of 4,4,4 */
PetscErrorCode MatMultAdd_SeqBAIJ_12_ver2(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, *y = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, *zarray, *yarray;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx, *ridx = NULL;
  PetscInt           mbs      = a->mbs, i, j, n;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  v = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 12 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n   = ii[i + 1] - ii[i];
    idx = ij + ii[i];

    if (usecprow) {
      y = yarray + 12 * ridx[i];
      z = zarray + 12 * ridx[i];
    }
    sum1  = y[0];
    sum2  = y[1];
    sum3  = y[2];
    sum4  = y[3];
    sum5  = y[4];
    sum6  = y[5];
    sum7  = y[6];
    sum8  = y[7];
    sum9  = y[8];
    sum10 = y[9];
    sum11 = y[10];
    sum12 = y[11];

    for (j = 0; j < n; j++) {
      xb = x + 12 * (idx[j]);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];

      sum1 += v[0] * x1 + v[12] * x2 + v[24] * x3 + v[36] * x4;
      sum2 += v[1] * x1 + v[13] * x2 + v[25] * x3 + v[37] * x4;
      sum3 += v[2] * x1 + v[14] * x2 + v[26] * x3 + v[38] * x4;
      sum4 += v[3] * x1 + v[15] * x2 + v[27] * x3 + v[39] * x4;
      sum5 += v[4] * x1 + v[16] * x2 + v[28] * x3 + v[40] * x4;
      sum6 += v[5] * x1 + v[17] * x2 + v[29] * x3 + v[41] * x4;
      sum7 += v[6] * x1 + v[18] * x2 + v[30] * x3 + v[42] * x4;
      sum8 += v[7] * x1 + v[19] * x2 + v[31] * x3 + v[43] * x4;
      sum9 += v[8] * x1 + v[20] * x2 + v[32] * x3 + v[44] * x4;
      sum10 += v[9] * x1 + v[21] * x2 + v[33] * x3 + v[45] * x4;
      sum11 += v[10] * x1 + v[22] * x2 + v[34] * x3 + v[46] * x4;
      sum12 += v[11] * x1 + v[23] * x2 + v[35] * x3 + v[47] * x4;
      v += 48;

      x1 = xb[4];
      x2 = xb[5];
      x3 = xb[6];
      x4 = xb[7];

      sum1 += v[0] * x1 + v[12] * x2 + v[24] * x3 + v[36] * x4;
      sum2 += v[1] * x1 + v[13] * x2 + v[25] * x3 + v[37] * x4;
      sum3 += v[2] * x1 + v[14] * x2 + v[26] * x3 + v[38] * x4;
      sum4 += v[3] * x1 + v[15] * x2 + v[27] * x3 + v[39] * x4;
      sum5 += v[4] * x1 + v[16] * x2 + v[28] * x3 + v[40] * x4;
      sum6 += v[5] * x1 + v[17] * x2 + v[29] * x3 + v[41] * x4;
      sum7 += v[6] * x1 + v[18] * x2 + v[30] * x3 + v[42] * x4;
      sum8 += v[7] * x1 + v[19] * x2 + v[31] * x3 + v[43] * x4;
      sum9 += v[8] * x1 + v[20] * x2 + v[32] * x3 + v[44] * x4;
      sum10 += v[9] * x1 + v[21] * x2 + v[33] * x3 + v[45] * x4;
      sum11 += v[10] * x1 + v[22] * x2 + v[34] * x3 + v[46] * x4;
      sum12 += v[11] * x1 + v[23] * x2 + v[35] * x3 + v[47] * x4;
      v += 48;

      x1 = xb[8];
      x2 = xb[9];
      x3 = xb[10];
      x4 = xb[11];
      sum1 += v[0] * x1 + v[12] * x2 + v[24] * x3 + v[36] * x4;
      sum2 += v[1] * x1 + v[13] * x2 + v[25] * x3 + v[37] * x4;
      sum3 += v[2] * x1 + v[14] * x2 + v[26] * x3 + v[38] * x4;
      sum4 += v[3] * x1 + v[15] * x2 + v[27] * x3 + v[39] * x4;
      sum5 += v[4] * x1 + v[16] * x2 + v[28] * x3 + v[40] * x4;
      sum6 += v[5] * x1 + v[17] * x2 + v[29] * x3 + v[41] * x4;
      sum7 += v[6] * x1 + v[18] * x2 + v[30] * x3 + v[42] * x4;
      sum8 += v[7] * x1 + v[19] * x2 + v[31] * x3 + v[43] * x4;
      sum9 += v[8] * x1 + v[20] * x2 + v[32] * x3 + v[44] * x4;
      sum10 += v[9] * x1 + v[21] * x2 + v[33] * x3 + v[45] * x4;
      sum11 += v[10] * x1 + v[22] * x2 + v[34] * x3 + v[46] * x4;
      sum12 += v[11] * x1 + v[23] * x2 + v[35] * x3 + v[47] * x4;
      v += 48;
    }
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    if (!usecprow) {
      y += 12;
      z += 12;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(288.0 * a->nz - 12.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

#if defined(PETSC_HAVE_IMMINTRIN_H) && defined(__AVX2__) && defined(__FMA__) && defined(PETSC_USE_REAL_DOUBLE) && !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_64BIT_INDICES)
PetscErrorCode MatMult_SeqBAIJ_12_AVX2(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, *zarray;
  const PetscScalar *x, *work;
  const MatScalar   *v = a->a;
  PetscInt           mbs, i, j, n;
  const PetscInt    *idx = a->j, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;
  const PetscInt     bs = 12, bs2 = 144;

  __m256d a0, a1, a2, a3, a4, a5;
  __m256d w0, w1, w2, w3;
  __m256d z0, z1, z2;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, bs * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    z0 = _mm256_setzero_pd();
    z1 = _mm256_setzero_pd();
    z2 = _mm256_setzero_pd();

    n = ii[1] - ii[0];
    ii++;
    for (j = 0; j < n; j++) {
      work = x + bs * (*idx++);

      /* first column of a */
      w0 = _mm256_set1_pd(work[0]);
      a0 = _mm256_loadu_pd(v + 0);
      z0 = _mm256_fmadd_pd(a0, w0, z0);
      a1 = _mm256_loadu_pd(v + 4);
      z1 = _mm256_fmadd_pd(a1, w0, z1);
      a2 = _mm256_loadu_pd(v + 8);
      z2 = _mm256_fmadd_pd(a2, w0, z2);

      /* second column of a */
      w1 = _mm256_set1_pd(work[1]);
      a3 = _mm256_loadu_pd(v + 12);
      z0 = _mm256_fmadd_pd(a3, w1, z0);
      a4 = _mm256_loadu_pd(v + 16);
      z1 = _mm256_fmadd_pd(a4, w1, z1);
      a5 = _mm256_loadu_pd(v + 20);
      z2 = _mm256_fmadd_pd(a5, w1, z2);

      /* third column of a */
      w2 = _mm256_set1_pd(work[2]);
      a0 = _mm256_loadu_pd(v + 24);
      z0 = _mm256_fmadd_pd(a0, w2, z0);
      a1 = _mm256_loadu_pd(v + 28);
      z1 = _mm256_fmadd_pd(a1, w2, z1);
      a2 = _mm256_loadu_pd(v + 32);
      z2 = _mm256_fmadd_pd(a2, w2, z2);

      /* fourth column of a */
      w3 = _mm256_set1_pd(work[3]);
      a3 = _mm256_loadu_pd(v + 36);
      z0 = _mm256_fmadd_pd(a3, w3, z0);
      a4 = _mm256_loadu_pd(v + 40);
      z1 = _mm256_fmadd_pd(a4, w3, z1);
      a5 = _mm256_loadu_pd(v + 44);
      z2 = _mm256_fmadd_pd(a5, w3, z2);

      /* fifth column of a */
      w0 = _mm256_set1_pd(work[4]);
      a0 = _mm256_loadu_pd(v + 48);
      z0 = _mm256_fmadd_pd(a0, w0, z0);
      a1 = _mm256_loadu_pd(v + 52);
      z1 = _mm256_fmadd_pd(a1, w0, z1);
      a2 = _mm256_loadu_pd(v + 56);
      z2 = _mm256_fmadd_pd(a2, w0, z2);

      /* sixth column of a */
      w1 = _mm256_set1_pd(work[5]);
      a3 = _mm256_loadu_pd(v + 60);
      z0 = _mm256_fmadd_pd(a3, w1, z0);
      a4 = _mm256_loadu_pd(v + 64);
      z1 = _mm256_fmadd_pd(a4, w1, z1);
      a5 = _mm256_loadu_pd(v + 68);
      z2 = _mm256_fmadd_pd(a5, w1, z2);

      /* seventh column of a */
      w2 = _mm256_set1_pd(work[6]);
      a0 = _mm256_loadu_pd(v + 72);
      z0 = _mm256_fmadd_pd(a0, w2, z0);
      a1 = _mm256_loadu_pd(v + 76);
      z1 = _mm256_fmadd_pd(a1, w2, z1);
      a2 = _mm256_loadu_pd(v + 80);
      z2 = _mm256_fmadd_pd(a2, w2, z2);

      /* eighth column of a */
      w3 = _mm256_set1_pd(work[7]);
      a3 = _mm256_loadu_pd(v + 84);
      z0 = _mm256_fmadd_pd(a3, w3, z0);
      a4 = _mm256_loadu_pd(v + 88);
      z1 = _mm256_fmadd_pd(a4, w3, z1);
      a5 = _mm256_loadu_pd(v + 92);
      z2 = _mm256_fmadd_pd(a5, w3, z2);

      /* ninth column of a */
      w0 = _mm256_set1_pd(work[8]);
      a0 = _mm256_loadu_pd(v + 96);
      z0 = _mm256_fmadd_pd(a0, w0, z0);
      a1 = _mm256_loadu_pd(v + 100);
      z1 = _mm256_fmadd_pd(a1, w0, z1);
      a2 = _mm256_loadu_pd(v + 104);
      z2 = _mm256_fmadd_pd(a2, w0, z2);

      /* tenth column of a */
      w1 = _mm256_set1_pd(work[9]);
      a3 = _mm256_loadu_pd(v + 108);
      z0 = _mm256_fmadd_pd(a3, w1, z0);
      a4 = _mm256_loadu_pd(v + 112);
      z1 = _mm256_fmadd_pd(a4, w1, z1);
      a5 = _mm256_loadu_pd(v + 116);
      z2 = _mm256_fmadd_pd(a5, w1, z2);

      /* eleventh column of a */
      w2 = _mm256_set1_pd(work[10]);
      a0 = _mm256_loadu_pd(v + 120);
      z0 = _mm256_fmadd_pd(a0, w2, z0);
      a1 = _mm256_loadu_pd(v + 124);
      z1 = _mm256_fmadd_pd(a1, w2, z1);
      a2 = _mm256_loadu_pd(v + 128);
      z2 = _mm256_fmadd_pd(a2, w2, z2);

      /* twelveth column of a */
      w3 = _mm256_set1_pd(work[11]);
      a3 = _mm256_loadu_pd(v + 132);
      z0 = _mm256_fmadd_pd(a3, w3, z0);
      a4 = _mm256_loadu_pd(v + 136);
      z1 = _mm256_fmadd_pd(a4, w3, z1);
      a5 = _mm256_loadu_pd(v + 140);
      z2 = _mm256_fmadd_pd(a5, w3, z2);

      v += bs2;
    }
    if (usecprow) z = zarray + bs * ridx[i];
    _mm256_storeu_pd(&z[0], z0);
    _mm256_storeu_pd(&z[4], z1);
    _mm256_storeu_pd(&z[8], z2);
    if (!usecprow) z += bs;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(2.0 * a->nz * bs2 - bs * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}
#endif

/* MatMult_SeqBAIJ_15 version 1: Columns in the block are accessed one at a time */
/* Default MatMult for block size 15 */
PetscErrorCode MatMult_SeqBAIJ_15_ver1(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12, sum13, sum14, sum15;
  const PetscScalar *x, *xb;
  PetscScalar       *zarray, xv;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx;
  PetscInt           mbs, i, j, k, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  v = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 15 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n     = ii[i + 1] - ii[i];
    idx   = ij + ii[i];
    sum1  = 0.0;
    sum2  = 0.0;
    sum3  = 0.0;
    sum4  = 0.0;
    sum5  = 0.0;
    sum6  = 0.0;
    sum7  = 0.0;
    sum8  = 0.0;
    sum9  = 0.0;
    sum10 = 0.0;
    sum11 = 0.0;
    sum12 = 0.0;
    sum13 = 0.0;
    sum14 = 0.0;
    sum15 = 0.0;

    for (j = 0; j < n; j++) {
      xb = x + 15 * (idx[j]);

      for (k = 0; k < 15; k++) {
        xv = xb[k];
        sum1 += v[0] * xv;
        sum2 += v[1] * xv;
        sum3 += v[2] * xv;
        sum4 += v[3] * xv;
        sum5 += v[4] * xv;
        sum6 += v[5] * xv;
        sum7 += v[6] * xv;
        sum8 += v[7] * xv;
        sum9 += v[8] * xv;
        sum10 += v[9] * xv;
        sum11 += v[10] * xv;
        sum12 += v[11] * xv;
        sum13 += v[12] * xv;
        sum14 += v[13] * xv;
        sum15 += v[14] * xv;
        v += 15;
      }
    }
    if (usecprow) z = zarray + 15 * ridx[i];
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    z[12] = sum13;
    z[13] = sum14;
    z[14] = sum15;

    if (!usecprow) z += 15;
  }

  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(450.0 * a->nz - 15.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

/* MatMult_SeqBAIJ_15_ver2 : Columns in the block are accessed in sets of 4,4,4,3 */
PetscErrorCode MatMult_SeqBAIJ_15_ver2(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12, sum13, sum14, sum15;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, *zarray;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx;
  PetscInt           mbs, i, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  v = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 15 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n     = ii[i + 1] - ii[i];
    idx   = ij + ii[i];
    sum1  = 0.0;
    sum2  = 0.0;
    sum3  = 0.0;
    sum4  = 0.0;
    sum5  = 0.0;
    sum6  = 0.0;
    sum7  = 0.0;
    sum8  = 0.0;
    sum9  = 0.0;
    sum10 = 0.0;
    sum11 = 0.0;
    sum12 = 0.0;
    sum13 = 0.0;
    sum14 = 0.0;
    sum15 = 0.0;

    for (j = 0; j < n; j++) {
      xb = x + 15 * (idx[j]);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];

      sum1 += v[0] * x1 + v[15] * x2 + v[30] * x3 + v[45] * x4;
      sum2 += v[1] * x1 + v[16] * x2 + v[31] * x3 + v[46] * x4;
      sum3 += v[2] * x1 + v[17] * x2 + v[32] * x3 + v[47] * x4;
      sum4 += v[3] * x1 + v[18] * x2 + v[33] * x3 + v[48] * x4;
      sum5 += v[4] * x1 + v[19] * x2 + v[34] * x3 + v[49] * x4;
      sum6 += v[5] * x1 + v[20] * x2 + v[35] * x3 + v[50] * x4;
      sum7 += v[6] * x1 + v[21] * x2 + v[36] * x3 + v[51] * x4;
      sum8 += v[7] * x1 + v[22] * x2 + v[37] * x3 + v[52] * x4;
      sum9 += v[8] * x1 + v[23] * x2 + v[38] * x3 + v[53] * x4;
      sum10 += v[9] * x1 + v[24] * x2 + v[39] * x3 + v[54] * x4;
      sum11 += v[10] * x1 + v[25] * x2 + v[40] * x3 + v[55] * x4;
      sum12 += v[11] * x1 + v[26] * x2 + v[41] * x3 + v[56] * x4;
      sum13 += v[12] * x1 + v[27] * x2 + v[42] * x3 + v[57] * x4;
      sum14 += v[13] * x1 + v[28] * x2 + v[43] * x3 + v[58] * x4;
      sum15 += v[14] * x1 + v[29] * x2 + v[44] * x3 + v[59] * x4;

      v += 60;

      x1 = xb[4];
      x2 = xb[5];
      x3 = xb[6];
      x4 = xb[7];

      sum1 += v[0] * x1 + v[15] * x2 + v[30] * x3 + v[45] * x4;
      sum2 += v[1] * x1 + v[16] * x2 + v[31] * x3 + v[46] * x4;
      sum3 += v[2] * x1 + v[17] * x2 + v[32] * x3 + v[47] * x4;
      sum4 += v[3] * x1 + v[18] * x2 + v[33] * x3 + v[48] * x4;
      sum5 += v[4] * x1 + v[19] * x2 + v[34] * x3 + v[49] * x4;
      sum6 += v[5] * x1 + v[20] * x2 + v[35] * x3 + v[50] * x4;
      sum7 += v[6] * x1 + v[21] * x2 + v[36] * x3 + v[51] * x4;
      sum8 += v[7] * x1 + v[22] * x2 + v[37] * x3 + v[52] * x4;
      sum9 += v[8] * x1 + v[23] * x2 + v[38] * x3 + v[53] * x4;
      sum10 += v[9] * x1 + v[24] * x2 + v[39] * x3 + v[54] * x4;
      sum11 += v[10] * x1 + v[25] * x2 + v[40] * x3 + v[55] * x4;
      sum12 += v[11] * x1 + v[26] * x2 + v[41] * x3 + v[56] * x4;
      sum13 += v[12] * x1 + v[27] * x2 + v[42] * x3 + v[57] * x4;
      sum14 += v[13] * x1 + v[28] * x2 + v[43] * x3 + v[58] * x4;
      sum15 += v[14] * x1 + v[29] * x2 + v[44] * x3 + v[59] * x4;
      v += 60;

      x1 = xb[8];
      x2 = xb[9];
      x3 = xb[10];
      x4 = xb[11];
      sum1 += v[0] * x1 + v[15] * x2 + v[30] * x3 + v[45] * x4;
      sum2 += v[1] * x1 + v[16] * x2 + v[31] * x3 + v[46] * x4;
      sum3 += v[2] * x1 + v[17] * x2 + v[32] * x3 + v[47] * x4;
      sum4 += v[3] * x1 + v[18] * x2 + v[33] * x3 + v[48] * x4;
      sum5 += v[4] * x1 + v[19] * x2 + v[34] * x3 + v[49] * x4;
      sum6 += v[5] * x1 + v[20] * x2 + v[35] * x3 + v[50] * x4;
      sum7 += v[6] * x1 + v[21] * x2 + v[36] * x3 + v[51] * x4;
      sum8 += v[7] * x1 + v[22] * x2 + v[37] * x3 + v[52] * x4;
      sum9 += v[8] * x1 + v[23] * x2 + v[38] * x3 + v[53] * x4;
      sum10 += v[9] * x1 + v[24] * x2 + v[39] * x3 + v[54] * x4;
      sum11 += v[10] * x1 + v[25] * x2 + v[40] * x3 + v[55] * x4;
      sum12 += v[11] * x1 + v[26] * x2 + v[41] * x3 + v[56] * x4;
      sum13 += v[12] * x1 + v[27] * x2 + v[42] * x3 + v[57] * x4;
      sum14 += v[13] * x1 + v[28] * x2 + v[43] * x3 + v[58] * x4;
      sum15 += v[14] * x1 + v[29] * x2 + v[44] * x3 + v[59] * x4;
      v += 60;

      x1 = xb[12];
      x2 = xb[13];
      x3 = xb[14];
      sum1 += v[0] * x1 + v[15] * x2 + v[30] * x3;
      sum2 += v[1] * x1 + v[16] * x2 + v[31] * x3;
      sum3 += v[2] * x1 + v[17] * x2 + v[32] * x3;
      sum4 += v[3] * x1 + v[18] * x2 + v[33] * x3;
      sum5 += v[4] * x1 + v[19] * x2 + v[34] * x3;
      sum6 += v[5] * x1 + v[20] * x2 + v[35] * x3;
      sum7 += v[6] * x1 + v[21] * x2 + v[36] * x3;
      sum8 += v[7] * x1 + v[22] * x2 + v[37] * x3;
      sum9 += v[8] * x1 + v[23] * x2 + v[38] * x3;
      sum10 += v[9] * x1 + v[24] * x2 + v[39] * x3;
      sum11 += v[10] * x1 + v[25] * x2 + v[40] * x3;
      sum12 += v[11] * x1 + v[26] * x2 + v[41] * x3;
      sum13 += v[12] * x1 + v[27] * x2 + v[42] * x3;
      sum14 += v[13] * x1 + v[28] * x2 + v[43] * x3;
      sum15 += v[14] * x1 + v[29] * x2 + v[44] * x3;
      v += 45;
    }
    if (usecprow) z = zarray + 15 * ridx[i];
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    z[12] = sum13;
    z[13] = sum14;
    z[14] = sum15;

    if (!usecprow) z += 15;
  }

  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(450.0 * a->nz - 15.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

/* MatMult_SeqBAIJ_15_ver3 : Columns in the block are accessed in sets of 8,7 */
PetscErrorCode MatMult_SeqBAIJ_15_ver3(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12, sum13, sum14, sum15;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, x5, x6, x7, x8, *zarray;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx;
  PetscInt           mbs, i, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  v = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 15 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n     = ii[i + 1] - ii[i];
    idx   = ij + ii[i];
    sum1  = 0.0;
    sum2  = 0.0;
    sum3  = 0.0;
    sum4  = 0.0;
    sum5  = 0.0;
    sum6  = 0.0;
    sum7  = 0.0;
    sum8  = 0.0;
    sum9  = 0.0;
    sum10 = 0.0;
    sum11 = 0.0;
    sum12 = 0.0;
    sum13 = 0.0;
    sum14 = 0.0;
    sum15 = 0.0;

    for (j = 0; j < n; j++) {
      xb = x + 15 * (idx[j]);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      x6 = xb[5];
      x7 = xb[6];
      x8 = xb[7];

      sum1 += v[0] * x1 + v[15] * x2 + v[30] * x3 + v[45] * x4 + v[60] * x5 + v[75] * x6 + v[90] * x7 + v[105] * x8;
      sum2 += v[1] * x1 + v[16] * x2 + v[31] * x3 + v[46] * x4 + v[61] * x5 + v[76] * x6 + v[91] * x7 + v[106] * x8;
      sum3 += v[2] * x1 + v[17] * x2 + v[32] * x3 + v[47] * x4 + v[62] * x5 + v[77] * x6 + v[92] * x7 + v[107] * x8;
      sum4 += v[3] * x1 + v[18] * x2 + v[33] * x3 + v[48] * x4 + v[63] * x5 + v[78] * x6 + v[93] * x7 + v[108] * x8;
      sum5 += v[4] * x1 + v[19] * x2 + v[34] * x3 + v[49] * x4 + v[64] * x5 + v[79] * x6 + v[94] * x7 + v[109] * x8;
      sum6 += v[5] * x1 + v[20] * x2 + v[35] * x3 + v[50] * x4 + v[65] * x5 + v[80] * x6 + v[95] * x7 + v[110] * x8;
      sum7 += v[6] * x1 + v[21] * x2 + v[36] * x3 + v[51] * x4 + v[66] * x5 + v[81] * x6 + v[96] * x7 + v[111] * x8;
      sum8 += v[7] * x1 + v[22] * x2 + v[37] * x3 + v[52] * x4 + v[67] * x5 + v[82] * x6 + v[97] * x7 + v[112] * x8;
      sum9 += v[8] * x1 + v[23] * x2 + v[38] * x3 + v[53] * x4 + v[68] * x5 + v[83] * x6 + v[98] * x7 + v[113] * x8;
      sum10 += v[9] * x1 + v[24] * x2 + v[39] * x3 + v[54] * x4 + v[69] * x5 + v[84] * x6 + v[99] * x7 + v[114] * x8;
      sum11 += v[10] * x1 + v[25] * x2 + v[40] * x3 + v[55] * x4 + v[70] * x5 + v[85] * x6 + v[100] * x7 + v[115] * x8;
      sum12 += v[11] * x1 + v[26] * x2 + v[41] * x3 + v[56] * x4 + v[71] * x5 + v[86] * x6 + v[101] * x7 + v[116] * x8;
      sum13 += v[12] * x1 + v[27] * x2 + v[42] * x3 + v[57] * x4 + v[72] * x5 + v[87] * x6 + v[102] * x7 + v[117] * x8;
      sum14 += v[13] * x1 + v[28] * x2 + v[43] * x3 + v[58] * x4 + v[73] * x5 + v[88] * x6 + v[103] * x7 + v[118] * x8;
      sum15 += v[14] * x1 + v[29] * x2 + v[44] * x3 + v[59] * x4 + v[74] * x5 + v[89] * x6 + v[104] * x7 + v[119] * x8;
      v += 120;

      x1 = xb[8];
      x2 = xb[9];
      x3 = xb[10];
      x4 = xb[11];
      x5 = xb[12];
      x6 = xb[13];
      x7 = xb[14];

      sum1 += v[0] * x1 + v[15] * x2 + v[30] * x3 + v[45] * x4 + v[60] * x5 + v[75] * x6 + v[90] * x7;
      sum2 += v[1] * x1 + v[16] * x2 + v[31] * x3 + v[46] * x4 + v[61] * x5 + v[76] * x6 + v[91] * x7;
      sum3 += v[2] * x1 + v[17] * x2 + v[32] * x3 + v[47] * x4 + v[62] * x5 + v[77] * x6 + v[92] * x7;
      sum4 += v[3] * x1 + v[18] * x2 + v[33] * x3 + v[48] * x4 + v[63] * x5 + v[78] * x6 + v[93] * x7;
      sum5 += v[4] * x1 + v[19] * x2 + v[34] * x3 + v[49] * x4 + v[64] * x5 + v[79] * x6 + v[94] * x7;
      sum6 += v[5] * x1 + v[20] * x2 + v[35] * x3 + v[50] * x4 + v[65] * x5 + v[80] * x6 + v[95] * x7;
      sum7 += v[6] * x1 + v[21] * x2 + v[36] * x3 + v[51] * x4 + v[66] * x5 + v[81] * x6 + v[96] * x7;
      sum8 += v[7] * x1 + v[22] * x2 + v[37] * x3 + v[52] * x4 + v[67] * x5 + v[82] * x6 + v[97] * x7;
      sum9 += v[8] * x1 + v[23] * x2 + v[38] * x3 + v[53] * x4 + v[68] * x5 + v[83] * x6 + v[98] * x7;
      sum10 += v[9] * x1 + v[24] * x2 + v[39] * x3 + v[54] * x4 + v[69] * x5 + v[84] * x6 + v[99] * x7;
      sum11 += v[10] * x1 + v[25] * x2 + v[40] * x3 + v[55] * x4 + v[70] * x5 + v[85] * x6 + v[100] * x7;
      sum12 += v[11] * x1 + v[26] * x2 + v[41] * x3 + v[56] * x4 + v[71] * x5 + v[86] * x6 + v[101] * x7;
      sum13 += v[12] * x1 + v[27] * x2 + v[42] * x3 + v[57] * x4 + v[72] * x5 + v[87] * x6 + v[102] * x7;
      sum14 += v[13] * x1 + v[28] * x2 + v[43] * x3 + v[58] * x4 + v[73] * x5 + v[88] * x6 + v[103] * x7;
      sum15 += v[14] * x1 + v[29] * x2 + v[44] * x3 + v[59] * x4 + v[74] * x5 + v[89] * x6 + v[104] * x7;
      v += 105;
    }
    if (usecprow) z = zarray + 15 * ridx[i];
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    z[12] = sum13;
    z[13] = sum14;
    z[14] = sum15;

    if (!usecprow) z += 15;
  }

  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(450.0 * a->nz - 15.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

/* MatMult_SeqBAIJ_15_ver4 : All columns in the block are accessed at once */
PetscErrorCode MatMult_SeqBAIJ_15_ver4(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11, sum12, sum13, sum14, sum15;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15, *zarray;
  const MatScalar   *v;
  const PetscInt    *ii, *ij = a->j, *idx;
  PetscInt           mbs, i, j, n, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  v = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, 15 * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n     = ii[i + 1] - ii[i];
    idx   = ij + ii[i];
    sum1  = 0.0;
    sum2  = 0.0;
    sum3  = 0.0;
    sum4  = 0.0;
    sum5  = 0.0;
    sum6  = 0.0;
    sum7  = 0.0;
    sum8  = 0.0;
    sum9  = 0.0;
    sum10 = 0.0;
    sum11 = 0.0;
    sum12 = 0.0;
    sum13 = 0.0;
    sum14 = 0.0;
    sum15 = 0.0;

    for (j = 0; j < n; j++) {
      xb  = x + 15 * (idx[j]);
      x1  = xb[0];
      x2  = xb[1];
      x3  = xb[2];
      x4  = xb[3];
      x5  = xb[4];
      x6  = xb[5];
      x7  = xb[6];
      x8  = xb[7];
      x9  = xb[8];
      x10 = xb[9];
      x11 = xb[10];
      x12 = xb[11];
      x13 = xb[12];
      x14 = xb[13];
      x15 = xb[14];

      sum1 += v[0] * x1 + v[15] * x2 + v[30] * x3 + v[45] * x4 + v[60] * x5 + v[75] * x6 + v[90] * x7 + v[105] * x8 + v[120] * x9 + v[135] * x10 + v[150] * x11 + v[165] * x12 + v[180] * x13 + v[195] * x14 + v[210] * x15;
      sum2 += v[1] * x1 + v[16] * x2 + v[31] * x3 + v[46] * x4 + v[61] * x5 + v[76] * x6 + v[91] * x7 + v[106] * x8 + v[121] * x9 + v[136] * x10 + v[151] * x11 + v[166] * x12 + v[181] * x13 + v[196] * x14 + v[211] * x15;
      sum3 += v[2] * x1 + v[17] * x2 + v[32] * x3 + v[47] * x4 + v[62] * x5 + v[77] * x6 + v[92] * x7 + v[107] * x8 + v[122] * x9 + v[137] * x10 + v[152] * x11 + v[167] * x12 + v[182] * x13 + v[197] * x14 + v[212] * x15;
      sum4 += v[3] * x1 + v[18] * x2 + v[33] * x3 + v[48] * x4 + v[63] * x5 + v[78] * x6 + v[93] * x7 + v[108] * x8 + v[123] * x9 + v[138] * x10 + v[153] * x11 + v[168] * x12 + v[183] * x13 + v[198] * x14 + v[213] * x15;
      sum5 += v[4] * x1 + v[19] * x2 + v[34] * x3 + v[49] * x4 + v[64] * x5 + v[79] * x6 + v[94] * x7 + v[109] * x8 + v[124] * x9 + v[139] * x10 + v[154] * x11 + v[169] * x12 + v[184] * x13 + v[199] * x14 + v[214] * x15;
      sum6 += v[5] * x1 + v[20] * x2 + v[35] * x3 + v[50] * x4 + v[65] * x5 + v[80] * x6 + v[95] * x7 + v[110] * x8 + v[125] * x9 + v[140] * x10 + v[155] * x11 + v[170] * x12 + v[185] * x13 + v[200] * x14 + v[215] * x15;
      sum7 += v[6] * x1 + v[21] * x2 + v[36] * x3 + v[51] * x4 + v[66] * x5 + v[81] * x6 + v[96] * x7 + v[111] * x8 + v[126] * x9 + v[141] * x10 + v[156] * x11 + v[171] * x12 + v[186] * x13 + v[201] * x14 + v[216] * x15;
      sum8 += v[7] * x1 + v[22] * x2 + v[37] * x3 + v[52] * x4 + v[67] * x5 + v[82] * x6 + v[97] * x7 + v[112] * x8 + v[127] * x9 + v[142] * x10 + v[157] * x11 + v[172] * x12 + v[187] * x13 + v[202] * x14 + v[217] * x15;
      sum9 += v[8] * x1 + v[23] * x2 + v[38] * x3 + v[53] * x4 + v[68] * x5 + v[83] * x6 + v[98] * x7 + v[113] * x8 + v[128] * x9 + v[143] * x10 + v[158] * x11 + v[173] * x12 + v[188] * x13 + v[203] * x14 + v[218] * x15;
      sum10 += v[9] * x1 + v[24] * x2 + v[39] * x3 + v[54] * x4 + v[69] * x5 + v[84] * x6 + v[99] * x7 + v[114] * x8 + v[129] * x9 + v[144] * x10 + v[159] * x11 + v[174] * x12 + v[189] * x13 + v[204] * x14 + v[219] * x15;
      sum11 += v[10] * x1 + v[25] * x2 + v[40] * x3 + v[55] * x4 + v[70] * x5 + v[85] * x6 + v[100] * x7 + v[115] * x8 + v[130] * x9 + v[145] * x10 + v[160] * x11 + v[175] * x12 + v[190] * x13 + v[205] * x14 + v[220] * x15;
      sum12 += v[11] * x1 + v[26] * x2 + v[41] * x3 + v[56] * x4 + v[71] * x5 + v[86] * x6 + v[101] * x7 + v[116] * x8 + v[131] * x9 + v[146] * x10 + v[161] * x11 + v[176] * x12 + v[191] * x13 + v[206] * x14 + v[221] * x15;
      sum13 += v[12] * x1 + v[27] * x2 + v[42] * x3 + v[57] * x4 + v[72] * x5 + v[87] * x6 + v[102] * x7 + v[117] * x8 + v[132] * x9 + v[147] * x10 + v[162] * x11 + v[177] * x12 + v[192] * x13 + v[207] * x14 + v[222] * x15;
      sum14 += v[13] * x1 + v[28] * x2 + v[43] * x3 + v[58] * x4 + v[73] * x5 + v[88] * x6 + v[103] * x7 + v[118] * x8 + v[133] * x9 + v[148] * x10 + v[163] * x11 + v[178] * x12 + v[193] * x13 + v[208] * x14 + v[223] * x15;
      sum15 += v[14] * x1 + v[29] * x2 + v[44] * x3 + v[59] * x4 + v[74] * x5 + v[89] * x6 + v[104] * x7 + v[119] * x8 + v[134] * x9 + v[149] * x10 + v[164] * x11 + v[179] * x12 + v[194] * x13 + v[209] * x14 + v[224] * x15;
      v += 225;
    }
    if (usecprow) z = zarray + 15 * ridx[i];
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    z[11] = sum12;
    z[12] = sum13;
    z[13] = sum14;
    z[14] = sum15;

    if (!usecprow) z += 15;
  }

  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(450.0 * a->nz - 15.0 * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

/*
    This will not work with MatScalar == float because it calls the BLAS
*/
PetscErrorCode MatMult_SeqBAIJ_N(Mat A, Vec xx, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, *work, *workt, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs, i, bs = A->rmap->bs, j, n, bs2 = a->bs2;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscInt           ncols, k;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayWrite(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
    PetscCall(PetscArrayzero(zarray, bs * a->mbs));
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  if (!a->mult_work) {
    k = PetscMax(A->rmap->n, A->cmap->n);
    PetscCall(PetscMalloc1(k + 1, &a->mult_work));
  }
  work = a->mult_work;
  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    ncols = n * bs;
    workt = work;
    for (j = 0; j < n; j++) {
      xb = x + bs * (*idx++);
      for (k = 0; k < bs; k++) workt[k] = xb[k];
      workt += bs;
    }
    if (usecprow) z = zarray + bs * ridx[i];
    PetscKernel_w_gets_Ar_times_v(bs, ncols, work, v, z);
    v += n * bs2;
    if (!usecprow) z += bs;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayWrite(zz, &zarray));
  PetscCall(PetscLogFlops(2.0 * a->nz * bs2 - bs * a->nonzerorowcnt));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_1(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  const PetscScalar *x;
  PetscScalar       *y, *z, sum;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, n, *ridx = NULL;
  const PetscInt    *idx, *ii;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &y, &z));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(z, y, mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (!usecprow) {
      sum = y[i];
    } else {
      sum = y[ridx[i]];
    }
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA); /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + n, n, 0, PETSC_PREFETCH_HINT_NTA);   /* Entries for the next row */
    PetscSparseDensePlusDot(sum, x, v, idx, n);
    v += n;
    idx += n;
    if (usecprow) {
      z[ridx[i]] = sum;
    } else {
      z[i] = sum;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &y, &z));
  PetscCall(PetscLogFlops(2.0 * a->nz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_2(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *y = NULL, *z = NULL, sum1, sum2;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, *yarray, *zarray;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, n, j;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 2 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (usecprow) {
      z = zarray + 2 * ridx[i];
      y = yarray + 2 * ridx[i];
    }
    sum1 = y[0];
    sum2 = y[1];
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);       /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 4 * n, 4 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 2 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];

      sum1 += v[0] * x1 + v[2] * x2;
      sum2 += v[1] * x1 + v[3] * x2;
      v += 4;
    }
    z[0] = sum1;
    z[1] = sum2;
    if (!usecprow) {
      z += 2;
      y += 2;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(4.0 * a->nz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_3(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *y = NULL, *z = NULL, sum1, sum2, sum3, x1, x2, x3, *yarray, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, j, n;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 3 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (usecprow) {
      z = zarray + 3 * ridx[i];
      y = yarray + 3 * ridx[i];
    }
    sum1 = y[0];
    sum2 = y[1];
    sum3 = y[2];
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);       /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 9 * n, 9 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 3 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      sum1 += v[0] * x1 + v[3] * x2 + v[6] * x3;
      sum2 += v[1] * x1 + v[4] * x2 + v[7] * x3;
      sum3 += v[2] * x1 + v[5] * x2 + v[8] * x3;
      v += 9;
    }
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    if (!usecprow) {
      z += 3;
      y += 3;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(18.0 * a->nz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_4(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *y = NULL, *z = NULL, sum1, sum2, sum3, sum4, x1, x2, x3, x4, *yarray, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, j, n;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 4 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (usecprow) {
      z = zarray + 4 * ridx[i];
      y = yarray + 4 * ridx[i];
    }
    sum1 = y[0];
    sum2 = y[1];
    sum3 = y[2];
    sum4 = y[3];
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 16 * n, 16 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 4 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      sum1 += v[0] * x1 + v[4] * x2 + v[8] * x3 + v[12] * x4;
      sum2 += v[1] * x1 + v[5] * x2 + v[9] * x3 + v[13] * x4;
      sum3 += v[2] * x1 + v[6] * x2 + v[10] * x3 + v[14] * x4;
      sum4 += v[3] * x1 + v[7] * x2 + v[11] * x3 + v[15] * x4;
      v += 16;
    }
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    if (!usecprow) {
      z += 4;
      y += 4;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(32.0 * a->nz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_5(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *y = NULL, *z = NULL, sum1, sum2, sum3, sum4, sum5, x1, x2, x3, x4, x5;
  const PetscScalar *x, *xb;
  PetscScalar       *yarray, *zarray;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, j, n;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 5 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (usecprow) {
      z = zarray + 5 * ridx[i];
      y = yarray + 5 * ridx[i];
    }
    sum1 = y[0];
    sum2 = y[1];
    sum3 = y[2];
    sum4 = y[3];
    sum5 = y[4];
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 25 * n, 25 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 5 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      sum1 += v[0] * x1 + v[5] * x2 + v[10] * x3 + v[15] * x4 + v[20] * x5;
      sum2 += v[1] * x1 + v[6] * x2 + v[11] * x3 + v[16] * x4 + v[21] * x5;
      sum3 += v[2] * x1 + v[7] * x2 + v[12] * x3 + v[17] * x4 + v[22] * x5;
      sum4 += v[3] * x1 + v[8] * x2 + v[13] * x3 + v[18] * x4 + v[23] * x5;
      sum5 += v[4] * x1 + v[9] * x2 + v[14] * x3 + v[19] * x4 + v[24] * x5;
      v += 25;
    }
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    z[4] = sum5;
    if (!usecprow) {
      z += 5;
      y += 5;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(50.0 * a->nz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_6(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *y = NULL, *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, x5, x6, *yarray, *zarray;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, j, n;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 6 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (usecprow) {
      z = zarray + 6 * ridx[i];
      y = yarray + 6 * ridx[i];
    }
    sum1 = y[0];
    sum2 = y[1];
    sum3 = y[2];
    sum4 = y[3];
    sum5 = y[4];
    sum6 = y[5];
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 36 * n, 36 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 6 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      x6 = xb[5];
      sum1 += v[0] * x1 + v[6] * x2 + v[12] * x3 + v[18] * x4 + v[24] * x5 + v[30] * x6;
      sum2 += v[1] * x1 + v[7] * x2 + v[13] * x3 + v[19] * x4 + v[25] * x5 + v[31] * x6;
      sum3 += v[2] * x1 + v[8] * x2 + v[14] * x3 + v[20] * x4 + v[26] * x5 + v[32] * x6;
      sum4 += v[3] * x1 + v[9] * x2 + v[15] * x3 + v[21] * x4 + v[27] * x5 + v[33] * x6;
      sum5 += v[4] * x1 + v[10] * x2 + v[16] * x3 + v[22] * x4 + v[28] * x5 + v[34] * x6;
      sum6 += v[5] * x1 + v[11] * x2 + v[17] * x3 + v[23] * x4 + v[29] * x5 + v[35] * x6;
      v += 36;
    }
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    z[4] = sum5;
    z[5] = sum6;
    if (!usecprow) {
      z += 6;
      y += 6;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(72.0 * a->nz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_7(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *y = NULL, *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, x5, x6, x7, *yarray, *zarray;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, j, n;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 7 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (usecprow) {
      z = zarray + 7 * ridx[i];
      y = yarray + 7 * ridx[i];
    }
    sum1 = y[0];
    sum2 = y[1];
    sum3 = y[2];
    sum4 = y[3];
    sum5 = y[4];
    sum6 = y[5];
    sum7 = y[6];
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 49 * n, 49 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb = x + 7 * (*idx++);
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      x6 = xb[5];
      x7 = xb[6];
      sum1 += v[0] * x1 + v[7] * x2 + v[14] * x3 + v[21] * x4 + v[28] * x5 + v[35] * x6 + v[42] * x7;
      sum2 += v[1] * x1 + v[8] * x2 + v[15] * x3 + v[22] * x4 + v[29] * x5 + v[36] * x6 + v[43] * x7;
      sum3 += v[2] * x1 + v[9] * x2 + v[16] * x3 + v[23] * x4 + v[30] * x5 + v[37] * x6 + v[44] * x7;
      sum4 += v[3] * x1 + v[10] * x2 + v[17] * x3 + v[24] * x4 + v[31] * x5 + v[38] * x6 + v[45] * x7;
      sum5 += v[4] * x1 + v[11] * x2 + v[18] * x3 + v[25] * x4 + v[32] * x5 + v[39] * x6 + v[46] * x7;
      sum6 += v[5] * x1 + v[12] * x2 + v[19] * x3 + v[26] * x4 + v[33] * x5 + v[40] * x6 + v[47] * x7;
      sum7 += v[6] * x1 + v[13] * x2 + v[20] * x3 + v[27] * x4 + v[34] * x5 + v[41] * x6 + v[48] * x7;
      v += 49;
    }
    z[0] = sum1;
    z[1] = sum2;
    z[2] = sum3;
    z[3] = sum4;
    z[4] = sum5;
    z[5] = sum6;
    z[6] = sum7;
    if (!usecprow) {
      z += 7;
      y += 7;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(98.0 * a->nz));
  PetscFunctionReturn(0);
}

#if defined(PETSC_HAVE_IMMINTRIN_H) && defined(__AVX2__) && defined(__FMA__) && defined(PETSC_USE_REAL_DOUBLE) && !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_64BIT_INDICES)
PetscErrorCode MatMultAdd_SeqBAIJ_9_AVX2(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, *work, *workt, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs, i, j, n;
  PetscInt           k;
  PetscBool          usecprow = a->compressedrow.use;
  const PetscInt    *idx, *ii, *ridx = NULL, bs = 9, bs2 = 81;

  __m256d a0, a1, a2, a3, a4, a5;
  __m256d w0, w1, w2, w3;
  __m256d z0, z1, z2;
  __m256i mask1 = _mm256_set_epi64x(0LL, 0LL, 0LL, 1LL << 63);

  PetscFunctionBegin;
  PetscCall(VecCopy(yy, zz));
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArray(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  if (!a->mult_work) {
    k = PetscMax(A->rmap->n, A->cmap->n);
    PetscCall(PetscMalloc1(k + 1, &a->mult_work));
  }

  work = a->mult_work;
  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    workt = work;
    for (j = 0; j < n; j++) {
      xb = x + bs * (*idx++);
      for (k = 0; k < bs; k++) workt[k] = xb[k];
      workt += bs;
    }
    if (usecprow) z = zarray + bs * ridx[i];

    z0 = _mm256_loadu_pd(&z[0]);
    z1 = _mm256_loadu_pd(&z[4]);
    z2 = _mm256_set1_pd(z[8]);

    for (j = 0; j < n; j++) {
      /* first column of a */
      w0 = _mm256_set1_pd(work[j * 9]);
      a0 = _mm256_loadu_pd(&v[j * 81]);
      z0 = _mm256_fmadd_pd(a0, w0, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 4]);
      z1 = _mm256_fmadd_pd(a1, w0, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 8]);
      z2 = _mm256_fmadd_pd(a2, w0, z2);

      /* second column of a */
      w1 = _mm256_set1_pd(work[j * 9 + 1]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 9]);
      z0 = _mm256_fmadd_pd(a0, w1, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 13]);
      z1 = _mm256_fmadd_pd(a1, w1, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 17]);
      z2 = _mm256_fmadd_pd(a2, w1, z2);

      /* third column of a */
      w2 = _mm256_set1_pd(work[j * 9 + 2]);
      a3 = _mm256_loadu_pd(&v[j * 81 + 18]);
      z0 = _mm256_fmadd_pd(a3, w2, z0);
      a4 = _mm256_loadu_pd(&v[j * 81 + 22]);
      z1 = _mm256_fmadd_pd(a4, w2, z1);
      a5 = _mm256_loadu_pd(&v[j * 81 + 26]);
      z2 = _mm256_fmadd_pd(a5, w2, z2);

      /* fourth column of a */
      w3 = _mm256_set1_pd(work[j * 9 + 3]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 27]);
      z0 = _mm256_fmadd_pd(a0, w3, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 31]);
      z1 = _mm256_fmadd_pd(a1, w3, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 35]);
      z2 = _mm256_fmadd_pd(a2, w3, z2);

      /* fifth column of a */
      w0 = _mm256_set1_pd(work[j * 9 + 4]);
      a3 = _mm256_loadu_pd(&v[j * 81 + 36]);
      z0 = _mm256_fmadd_pd(a3, w0, z0);
      a4 = _mm256_loadu_pd(&v[j * 81 + 40]);
      z1 = _mm256_fmadd_pd(a4, w0, z1);
      a5 = _mm256_loadu_pd(&v[j * 81 + 44]);
      z2 = _mm256_fmadd_pd(a5, w0, z2);

      /* sixth column of a */
      w1 = _mm256_set1_pd(work[j * 9 + 5]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 45]);
      z0 = _mm256_fmadd_pd(a0, w1, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 49]);
      z1 = _mm256_fmadd_pd(a1, w1, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 53]);
      z2 = _mm256_fmadd_pd(a2, w1, z2);

      /* seventh column of a */
      w2 = _mm256_set1_pd(work[j * 9 + 6]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 54]);
      z0 = _mm256_fmadd_pd(a0, w2, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 58]);
      z1 = _mm256_fmadd_pd(a1, w2, z1);
      a2 = _mm256_loadu_pd(&v[j * 81 + 62]);
      z2 = _mm256_fmadd_pd(a2, w2, z2);

      /* eighth column of a */
      w3 = _mm256_set1_pd(work[j * 9 + 7]);
      a3 = _mm256_loadu_pd(&v[j * 81 + 63]);
      z0 = _mm256_fmadd_pd(a3, w3, z0);
      a4 = _mm256_loadu_pd(&v[j * 81 + 67]);
      z1 = _mm256_fmadd_pd(a4, w3, z1);
      a5 = _mm256_loadu_pd(&v[j * 81 + 71]);
      z2 = _mm256_fmadd_pd(a5, w3, z2);

      /* ninth column of a */
      w0 = _mm256_set1_pd(work[j * 9 + 8]);
      a0 = _mm256_loadu_pd(&v[j * 81 + 72]);
      z0 = _mm256_fmadd_pd(a0, w0, z0);
      a1 = _mm256_loadu_pd(&v[j * 81 + 76]);
      z1 = _mm256_fmadd_pd(a1, w0, z1);
      a2 = _mm256_maskload_pd(&v[j * 81 + 80], mask1);
      z2 = _mm256_fmadd_pd(a2, w0, z2);
    }

    _mm256_storeu_pd(&z[0], z0);
    _mm256_storeu_pd(&z[4], z1);
    _mm256_maskstore_pd(&z[8], mask1, z2);

    v += n * bs2;
    if (!usecprow) z += bs;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArray(zz, &zarray));
  PetscCall(PetscLogFlops(162.0 * a->nz));
  PetscFunctionReturn(0);
}
#endif

PetscErrorCode MatMultAdd_SeqBAIJ_11(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *y = NULL, *z = NULL, sum1, sum2, sum3, sum4, sum5, sum6, sum7, sum8, sum9, sum10, sum11;
  const PetscScalar *x, *xb;
  PetscScalar        x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, *yarray, *zarray;
  const MatScalar   *v;
  PetscInt           mbs = a->mbs, i, j, n;
  const PetscInt    *idx, *ii, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArrayPair(yy, zz, &yarray, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    if (zz != yy) { PetscCall(PetscArraycpy(zarray, yarray, 7 * mbs)); }
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    ii = a->i;
    y  = yarray;
    z  = zarray;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    if (usecprow) {
      z = zarray + 11 * ridx[i];
      y = yarray + 11 * ridx[i];
    }
    sum1  = y[0];
    sum2  = y[1];
    sum3  = y[2];
    sum4  = y[3];
    sum5  = y[4];
    sum6  = y[5];
    sum7  = y[6];
    sum8  = y[7];
    sum9  = y[8];
    sum10 = y[9];
    sum11 = y[10];
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);           /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 121 * n, 121 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    for (j = 0; j < n; j++) {
      xb  = x + 11 * (*idx++);
      x1  = xb[0];
      x2  = xb[1];
      x3  = xb[2];
      x4  = xb[3];
      x5  = xb[4];
      x6  = xb[5];
      x7  = xb[6];
      x8  = xb[7];
      x9  = xb[8];
      x10 = xb[9];
      x11 = xb[10];
      sum1 += v[0] * x1 + v[11] * x2 + v[2 * 11] * x3 + v[3 * 11] * x4 + v[4 * 11] * x5 + v[5 * 11] * x6 + v[6 * 11] * x7 + v[7 * 11] * x8 + v[8 * 11] * x9 + v[9 * 11] * x10 + v[10 * 11] * x11;
      sum2 += v[1 + 0] * x1 + v[1 + 11] * x2 + v[1 + 2 * 11] * x3 + v[1 + 3 * 11] * x4 + v[1 + 4 * 11] * x5 + v[1 + 5 * 11] * x6 + v[1 + 6 * 11] * x7 + v[1 + 7 * 11] * x8 + v[1 + 8 * 11] * x9 + v[1 + 9 * 11] * x10 + v[1 + 10 * 11] * x11;
      sum3 += v[2 + 0] * x1 + v[2 + 11] * x2 + v[2 + 2 * 11] * x3 + v[2 + 3 * 11] * x4 + v[2 + 4 * 11] * x5 + v[2 + 5 * 11] * x6 + v[2 + 6 * 11] * x7 + v[2 + 7 * 11] * x8 + v[2 + 8 * 11] * x9 + v[2 + 9 * 11] * x10 + v[2 + 10 * 11] * x11;
      sum4 += v[3 + 0] * x1 + v[3 + 11] * x2 + v[3 + 2 * 11] * x3 + v[3 + 3 * 11] * x4 + v[3 + 4 * 11] * x5 + v[3 + 5 * 11] * x6 + v[3 + 6 * 11] * x7 + v[3 + 7 * 11] * x8 + v[3 + 8 * 11] * x9 + v[3 + 9 * 11] * x10 + v[3 + 10 * 11] * x11;
      sum5 += v[4 + 0] * x1 + v[4 + 11] * x2 + v[4 + 2 * 11] * x3 + v[4 + 3 * 11] * x4 + v[4 + 4 * 11] * x5 + v[4 + 5 * 11] * x6 + v[4 + 6 * 11] * x7 + v[4 + 7 * 11] * x8 + v[4 + 8 * 11] * x9 + v[4 + 9 * 11] * x10 + v[4 + 10 * 11] * x11;
      sum6 += v[5 + 0] * x1 + v[5 + 11] * x2 + v[5 + 2 * 11] * x3 + v[5 + 3 * 11] * x4 + v[5 + 4 * 11] * x5 + v[5 + 5 * 11] * x6 + v[5 + 6 * 11] * x7 + v[5 + 7 * 11] * x8 + v[5 + 8 * 11] * x9 + v[5 + 9 * 11] * x10 + v[5 + 10 * 11] * x11;
      sum7 += v[6 + 0] * x1 + v[6 + 11] * x2 + v[6 + 2 * 11] * x3 + v[6 + 3 * 11] * x4 + v[6 + 4 * 11] * x5 + v[6 + 5 * 11] * x6 + v[6 + 6 * 11] * x7 + v[6 + 7 * 11] * x8 + v[6 + 8 * 11] * x9 + v[6 + 9 * 11] * x10 + v[6 + 10 * 11] * x11;
      sum8 += v[7 + 0] * x1 + v[7 + 11] * x2 + v[7 + 2 * 11] * x3 + v[7 + 3 * 11] * x4 + v[7 + 4 * 11] * x5 + v[7 + 5 * 11] * x6 + v[7 + 6 * 11] * x7 + v[7 + 7 * 11] * x8 + v[7 + 8 * 11] * x9 + v[7 + 9 * 11] * x10 + v[7 + 10 * 11] * x11;
      sum9 += v[8 + 0] * x1 + v[8 + 11] * x2 + v[8 + 2 * 11] * x3 + v[8 + 3 * 11] * x4 + v[8 + 4 * 11] * x5 + v[8 + 5 * 11] * x6 + v[8 + 6 * 11] * x7 + v[8 + 7 * 11] * x8 + v[8 + 8 * 11] * x9 + v[8 + 9 * 11] * x10 + v[8 + 10 * 11] * x11;
      sum10 += v[9 + 0] * x1 + v[9 + 11] * x2 + v[9 + 2 * 11] * x3 + v[9 + 3 * 11] * x4 + v[9 + 4 * 11] * x5 + v[9 + 5 * 11] * x6 + v[9 + 6 * 11] * x7 + v[9 + 7 * 11] * x8 + v[9 + 8 * 11] * x9 + v[9 + 9 * 11] * x10 + v[9 + 10 * 11] * x11;
      sum11 += v[10 + 0] * x1 + v[10 + 11] * x2 + v[10 + 2 * 11] * x3 + v[10 + 3 * 11] * x4 + v[10 + 4 * 11] * x5 + v[10 + 5 * 11] * x6 + v[10 + 6 * 11] * x7 + v[10 + 7 * 11] * x8 + v[10 + 8 * 11] * x9 + v[10 + 9 * 11] * x10 + v[10 + 10 * 11] * x11;
      v += 121;
    }
    z[0]  = sum1;
    z[1]  = sum2;
    z[2]  = sum3;
    z[3]  = sum4;
    z[4]  = sum5;
    z[5]  = sum6;
    z[6]  = sum7;
    z[7]  = sum8;
    z[8]  = sum9;
    z[9]  = sum10;
    z[10] = sum11;
    if (!usecprow) {
      z += 11;
      y += 11;
    }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArrayPair(yy, zz, &yarray, &zarray));
  PetscCall(PetscLogFlops(242.0 * a->nz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultAdd_SeqBAIJ_N(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, *work, *workt, *zarray;
  const PetscScalar *x, *xb;
  const MatScalar   *v;
  PetscInt           mbs, i, bs = A->rmap->bs, j, n, bs2 = a->bs2;
  PetscInt           ncols, k;
  const PetscInt    *ridx     = NULL, *idx, *ii;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  PetscCall(VecCopy(yy, zz));
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArray(zz, &zarray));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = zarray;
  }

  if (!a->mult_work) {
    k = PetscMax(A->rmap->n, A->cmap->n);
    PetscCall(PetscMalloc1(k + 1, &a->mult_work));
  }
  work = a->mult_work;
  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    ncols = n * bs;
    workt = work;
    for (j = 0; j < n; j++) {
      xb = x + bs * (*idx++);
      for (k = 0; k < bs; k++) workt[k] = xb[k];
      workt += bs;
    }
    if (usecprow) z = zarray + bs * ridx[i];
    PetscKernel_w_gets_w_plus_Ar_times_v(bs, ncols, work, v, z);
    v += n * bs2;
    if (!usecprow) z += bs;
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArray(zz, &zarray));
  PetscCall(PetscLogFlops(2.0 * a->nz * bs2));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultHermitianTranspose_SeqBAIJ(Mat A, Vec xx, Vec zz) {
  PetscScalar zero = 0.0;

  PetscFunctionBegin;
  PetscCall(VecSet(zz, zero));
  PetscCall(MatMultHermitianTransposeAdd_SeqBAIJ(A, xx, zz, zz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultTranspose_SeqBAIJ(Mat A, Vec xx, Vec zz) {
  PetscScalar zero = 0.0;

  PetscFunctionBegin;
  PetscCall(VecSet(zz, zero));
  PetscCall(MatMultTransposeAdd_SeqBAIJ(A, xx, zz, zz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultHermitianTransposeAdd_SeqBAIJ(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z, x1, x2, x3, x4, x5;
  const PetscScalar *x, *xb = NULL;
  const MatScalar   *v;
  PetscInt           mbs, i, rval, bs     = A->rmap->bs, j, n;
  const PetscInt    *idx, *ii, *ib, *ridx = NULL;
  Mat_CompressedRow  cprow    = a->compressedrow;
  PetscBool          usecprow = cprow.use;

  PetscFunctionBegin;
  if (yy != zz) PetscCall(VecCopy(yy, zz));
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArray(zz, &z));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = cprow.nrows;
    ii   = cprow.i;
    ridx = cprow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    xb  = x;
  }

  switch (bs) {
  case 1:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + ridx[i];
      x1 = xb[0];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j];
        z[rval] += PetscConj(*v) * x1;
        v++;
      }
      if (!usecprow) xb++;
    }
    break;
  case 2:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 2 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 2;
        z[rval++] += PetscConj(v[0]) * x1 + PetscConj(v[1]) * x2;
        z[rval++] += PetscConj(v[2]) * x1 + PetscConj(v[3]) * x2;
        v += 4;
      }
      if (!usecprow) xb += 2;
    }
    break;
  case 3:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 3 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 3;
        z[rval++] += PetscConj(v[0]) * x1 + PetscConj(v[1]) * x2 + PetscConj(v[2]) * x3;
        z[rval++] += PetscConj(v[3]) * x1 + PetscConj(v[4]) * x2 + PetscConj(v[5]) * x3;
        z[rval++] += PetscConj(v[6]) * x1 + PetscConj(v[7]) * x2 + PetscConj(v[8]) * x3;
        v += 9;
      }
      if (!usecprow) xb += 3;
    }
    break;
  case 4:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 4 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 4;
        z[rval++] += PetscConj(v[0]) * x1 + PetscConj(v[1]) * x2 + PetscConj(v[2]) * x3 + PetscConj(v[3]) * x4;
        z[rval++] += PetscConj(v[4]) * x1 + PetscConj(v[5]) * x2 + PetscConj(v[6]) * x3 + PetscConj(v[7]) * x4;
        z[rval++] += PetscConj(v[8]) * x1 + PetscConj(v[9]) * x2 + PetscConj(v[10]) * x3 + PetscConj(v[11]) * x4;
        z[rval++] += PetscConj(v[12]) * x1 + PetscConj(v[13]) * x2 + PetscConj(v[14]) * x3 + PetscConj(v[15]) * x4;
        v += 16;
      }
      if (!usecprow) xb += 4;
    }
    break;
  case 5:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 5 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 5;
        z[rval++] += PetscConj(v[0]) * x1 + PetscConj(v[1]) * x2 + PetscConj(v[2]) * x3 + PetscConj(v[3]) * x4 + PetscConj(v[4]) * x5;
        z[rval++] += PetscConj(v[5]) * x1 + PetscConj(v[6]) * x2 + PetscConj(v[7]) * x3 + PetscConj(v[8]) * x4 + PetscConj(v[9]) * x5;
        z[rval++] += PetscConj(v[10]) * x1 + PetscConj(v[11]) * x2 + PetscConj(v[12]) * x3 + PetscConj(v[13]) * x4 + PetscConj(v[14]) * x5;
        z[rval++] += PetscConj(v[15]) * x1 + PetscConj(v[16]) * x2 + PetscConj(v[17]) * x3 + PetscConj(v[18]) * x4 + PetscConj(v[19]) * x5;
        z[rval++] += PetscConj(v[20]) * x1 + PetscConj(v[21]) * x2 + PetscConj(v[22]) * x3 + PetscConj(v[23]) * x4 + PetscConj(v[24]) * x5;
        v += 25;
      }
      if (!usecprow) xb += 5;
    }
    break;
  default: /* block sizes larger than 5 by 5 are handled by BLAS */ SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "block size larger than 5 is not supported yet");
#if 0
    {
      PetscInt          ncols,k,bs2=a->bs2;
      PetscScalar       *work,*workt,zb;
      const PetscScalar *xtmp;
      if (!a->mult_work) {
        k    = PetscMax(A->rmap->n,A->cmap->n);
        PetscCall(PetscMalloc1(k+1,&a->mult_work));
      }
      work = a->mult_work;
      xtmp = x;
      for (i=0; i<mbs; i++) {
        n     = ii[1] - ii[0]; ii++;
        ncols = n*bs;
        PetscCall(PetscArrayzero(work,ncols));
        if (usecprow) xtmp = x + bs*ridx[i];
        PetscKernel_w_gets_w_plus_trans_Ar_times_v(bs,ncols,xtmp,v,work);
        v += n*bs2;
        if (!usecprow) xtmp += bs;
        workt = work;
        for (j=0; j<n; j++) {
          zb = z + bs*(*idx++);
          for (k=0; k<bs; k++) zb[k] += workt[k] ;
          workt += bs;
        }
      }
    }
#endif
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArray(zz, &z));
  PetscCall(PetscLogFlops(2.0 * a->nz * a->bs2));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMultTransposeAdd_SeqBAIJ(Mat A, Vec xx, Vec yy, Vec zz) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *zb, *z, x1, x2, x3, x4, x5;
  const PetscScalar *x, *xb = NULL;
  const MatScalar   *v;
  PetscInt           mbs, i, rval, bs = A->rmap->bs, j, n, bs2 = a->bs2;
  const PetscInt    *idx, *ii, *ib, *ridx = NULL;
  Mat_CompressedRow  cprow    = a->compressedrow;
  PetscBool          usecprow = cprow.use;

  PetscFunctionBegin;
  if (yy != zz) PetscCall(VecCopy(yy, zz));
  PetscCall(VecGetArrayRead(xx, &x));
  PetscCall(VecGetArray(zz, &z));

  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = cprow.nrows;
    ii   = cprow.i;
    ridx = cprow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    xb  = x;
  }

  switch (bs) {
  case 1:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + ridx[i];
      x1 = xb[0];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j];
        z[rval] += *v * x1;
        v++;
      }
      if (!usecprow) xb++;
    }
    break;
  case 2:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 2 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 2;
        z[rval++] += v[0] * x1 + v[1] * x2;
        z[rval++] += v[2] * x1 + v[3] * x2;
        v += 4;
      }
      if (!usecprow) xb += 2;
    }
    break;
  case 3:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 3 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 3;
        z[rval++] += v[0] * x1 + v[1] * x2 + v[2] * x3;
        z[rval++] += v[3] * x1 + v[4] * x2 + v[5] * x3;
        z[rval++] += v[6] * x1 + v[7] * x2 + v[8] * x3;
        v += 9;
      }
      if (!usecprow) xb += 3;
    }
    break;
  case 4:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 4 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 4;
        z[rval++] += v[0] * x1 + v[1] * x2 + v[2] * x3 + v[3] * x4;
        z[rval++] += v[4] * x1 + v[5] * x2 + v[6] * x3 + v[7] * x4;
        z[rval++] += v[8] * x1 + v[9] * x2 + v[10] * x3 + v[11] * x4;
        z[rval++] += v[12] * x1 + v[13] * x2 + v[14] * x3 + v[15] * x4;
        v += 16;
      }
      if (!usecprow) xb += 4;
    }
    break;
  case 5:
    for (i = 0; i < mbs; i++) {
      if (usecprow) xb = x + 5 * ridx[i];
      x1 = xb[0];
      x2 = xb[1];
      x3 = xb[2];
      x4 = xb[3];
      x5 = xb[4];
      ib = idx + ii[0];
      n  = ii[1] - ii[0];
      ii++;
      for (j = 0; j < n; j++) {
        rval = ib[j] * 5;
        z[rval++] += v[0] * x1 + v[1] * x2 + v[2] * x3 + v[3] * x4 + v[4] * x5;
        z[rval++] += v[5] * x1 + v[6] * x2 + v[7] * x3 + v[8] * x4 + v[9] * x5;
        z[rval++] += v[10] * x1 + v[11] * x2 + v[12] * x3 + v[13] * x4 + v[14] * x5;
        z[rval++] += v[15] * x1 + v[16] * x2 + v[17] * x3 + v[18] * x4 + v[19] * x5;
        z[rval++] += v[20] * x1 + v[21] * x2 + v[22] * x3 + v[23] * x4 + v[24] * x5;
        v += 25;
      }
      if (!usecprow) xb += 5;
    }
    break;
  default: { /* block sizes larger then 5 by 5 are handled by BLAS */
    PetscInt           ncols, k;
    PetscScalar       *work, *workt;
    const PetscScalar *xtmp;
    if (!a->mult_work) {
      k = PetscMax(A->rmap->n, A->cmap->n);
      PetscCall(PetscMalloc1(k + 1, &a->mult_work));
    }
    work = a->mult_work;
    xtmp = x;
    for (i = 0; i < mbs; i++) {
      n = ii[1] - ii[0];
      ii++;
      ncols = n * bs;
      PetscCall(PetscArrayzero(work, ncols));
      if (usecprow) xtmp = x + bs * ridx[i];
      PetscKernel_w_gets_w_plus_trans_Ar_times_v(bs, ncols, xtmp, v, work);
      v += n * bs2;
      if (!usecprow) xtmp += bs;
      workt = work;
      for (j = 0; j < n; j++) {
        zb = z + bs * (*idx++);
        for (k = 0; k < bs; k++) zb[k] += workt[k];
        workt += bs;
      }
    }
  }
  }
  PetscCall(VecRestoreArrayRead(xx, &x));
  PetscCall(VecRestoreArray(zz, &z));
  PetscCall(PetscLogFlops(2.0 * a->nz * a->bs2));
  PetscFunctionReturn(0);
}

PetscErrorCode MatScale_SeqBAIJ(Mat inA, PetscScalar alpha) {
  Mat_SeqBAIJ *a       = (Mat_SeqBAIJ *)inA->data;
  PetscInt     totalnz = a->bs2 * a->nz;
  PetscScalar  oalpha  = alpha;
  PetscBLASInt one     = 1, tnz;

  PetscFunctionBegin;
  PetscCall(PetscBLASIntCast(totalnz, &tnz));
  PetscCallBLAS("BLASscal", BLASscal_(&tnz, &oalpha, a->a, &one));
  PetscCall(PetscLogFlops(totalnz));
  PetscFunctionReturn(0);
}

PetscErrorCode MatNorm_SeqBAIJ(Mat A, NormType type, PetscReal *norm) {
  Mat_SeqBAIJ *a   = (Mat_SeqBAIJ *)A->data;
  MatScalar   *v   = a->a;
  PetscReal    sum = 0.0;
  PetscInt     i, j, k, bs = A->rmap->bs, nz = a->nz, bs2 = a->bs2, k1;

  PetscFunctionBegin;
  if (type == NORM_FROBENIUS) {
#if defined(PETSC_USE_REAL___FP16)
    PetscBLASInt one = 1, cnt = bs2 * nz;
    PetscCallBLAS("BLASnrm2", *norm = BLASnrm2_(&cnt, v, &one));
#else
    for (i = 0; i < bs2 * nz; i++) {
      sum += PetscRealPart(PetscConj(*v) * (*v));
      v++;
    }
#endif
    *norm = PetscSqrtReal(sum);
    PetscCall(PetscLogFlops(2.0 * bs2 * nz));
  } else if (type == NORM_1) { /* maximum column sum */
    PetscReal *tmp;
    PetscInt  *bcol = a->j;
    PetscCall(PetscCalloc1(A->cmap->n + 1, &tmp));
    for (i = 0; i < nz; i++) {
      for (j = 0; j < bs; j++) {
        k1 = bs * (*bcol) + j; /* column index */
        for (k = 0; k < bs; k++) {
          tmp[k1] += PetscAbsScalar(*v);
          v++;
        }
      }
      bcol++;
    }
    *norm = 0.0;
    for (j = 0; j < A->cmap->n; j++) {
      if (tmp[j] > *norm) *norm = tmp[j];
    }
    PetscCall(PetscFree(tmp));
    PetscCall(PetscLogFlops(PetscMax(bs2 * nz - 1, 0)));
  } else if (type == NORM_INFINITY) { /* maximum row sum */
    *norm = 0.0;
    for (k = 0; k < bs; k++) {
      for (j = 0; j < a->mbs; j++) {
        v   = a->a + bs2 * a->i[j] + k;
        sum = 0.0;
        for (i = 0; i < a->i[j + 1] - a->i[j]; i++) {
          for (k1 = 0; k1 < bs; k1++) {
            sum += PetscAbsScalar(*v);
            v += bs;
          }
        }
        if (sum > *norm) *norm = sum;
      }
    }
    PetscCall(PetscLogFlops(PetscMax(bs2 * nz - 1, 0)));
  } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "No support for this norm yet");
  PetscFunctionReturn(0);
}

PetscErrorCode MatEqual_SeqBAIJ(Mat A, Mat B, PetscBool *flg) {
  Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data, *b = (Mat_SeqBAIJ *)B->data;

  PetscFunctionBegin;
  /* If the  matrix/block dimensions are not equal, or no of nonzeros or shift */
  if ((A->rmap->N != B->rmap->N) || (A->cmap->n != B->cmap->n) || (A->rmap->bs != B->rmap->bs) || (a->nz != b->nz)) {
    *flg = PETSC_FALSE;
    PetscFunctionReturn(0);
  }

  /* if the a->i are the same */
  PetscCall(PetscArraycmp(a->i, b->i, a->mbs + 1, flg));
  if (!*flg) PetscFunctionReturn(0);

  /* if a->j are the same */
  PetscCall(PetscArraycmp(a->j, b->j, a->nz, flg));
  if (!*flg) PetscFunctionReturn(0);

  /* if a->a are the same */
  PetscCall(PetscArraycmp(a->a, b->a, (a->nz) * (A->rmap->bs) * (B->rmap->bs), flg));
  PetscFunctionReturn(0);
}

PetscErrorCode MatGetDiagonal_SeqBAIJ(Mat A, Vec v) {
  Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data;
  PetscInt     i, j, k, n, row, bs, *ai, *aj, ambs, bs2;
  PetscScalar *x, zero = 0.0;
  MatScalar   *aa, *aa_j;

  PetscFunctionBegin;
  PetscCheck(!A->factortype, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Not for factored matrix");
  bs   = A->rmap->bs;
  aa   = a->a;
  ai   = a->i;
  aj   = a->j;
  ambs = a->mbs;
  bs2  = a->bs2;

  PetscCall(VecSet(v, zero));
  PetscCall(VecGetArray(v, &x));
  PetscCall(VecGetLocalSize(v, &n));
  PetscCheck(n == A->rmap->N, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Nonconforming matrix and vector");
  for (i = 0; i < ambs; i++) {
    for (j = ai[i]; j < ai[i + 1]; j++) {
      if (aj[j] == i) {
        row  = i * bs;
        aa_j = aa + j * bs2;
        for (k = 0; k < bs2; k += (bs + 1), row++) x[row] = aa_j[k];
        break;
      }
    }
  }
  PetscCall(VecRestoreArray(v, &x));
  PetscFunctionReturn(0);
}

PetscErrorCode MatDiagonalScale_SeqBAIJ(Mat A, Vec ll, Vec rr) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  const PetscScalar *l, *r, *li, *ri;
  PetscScalar        x;
  MatScalar         *aa, *v;
  PetscInt           i, j, k, lm, rn, M, m, n, mbs, tmp, bs, bs2, iai;
  const PetscInt    *ai, *aj;

  PetscFunctionBegin;
  ai  = a->i;
  aj  = a->j;
  aa  = a->a;
  m   = A->rmap->n;
  n   = A->cmap->n;
  bs  = A->rmap->bs;
  mbs = a->mbs;
  bs2 = a->bs2;
  if (ll) {
    PetscCall(VecGetArrayRead(ll, &l));
    PetscCall(VecGetLocalSize(ll, &lm));
    PetscCheck(lm == m, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Left scaling vector wrong length");
    for (i = 0; i < mbs; i++) { /* for each block row */
      M  = ai[i + 1] - ai[i];
      li = l + i * bs;
      v  = aa + bs2 * ai[i];
      for (j = 0; j < M; j++) { /* for each block */
        for (k = 0; k < bs2; k++) { (*v++) *= li[k % bs]; }
      }
    }
    PetscCall(VecRestoreArrayRead(ll, &l));
    PetscCall(PetscLogFlops(a->nz));
  }

  if (rr) {
    PetscCall(VecGetArrayRead(rr, &r));
    PetscCall(VecGetLocalSize(rr, &rn));
    PetscCheck(rn == n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Right scaling vector wrong length");
    for (i = 0; i < mbs; i++) { /* for each block row */
      iai = ai[i];
      M   = ai[i + 1] - iai;
      v   = aa + bs2 * iai;
      for (j = 0; j < M; j++) { /* for each block */
        ri = r + bs * aj[iai + j];
        for (k = 0; k < bs; k++) {
          x = ri[k];
          for (tmp = 0; tmp < bs; tmp++) v[tmp] *= x;
          v += bs;
        }
      }
    }
    PetscCall(VecRestoreArrayRead(rr, &r));
    PetscCall(PetscLogFlops(a->nz));
  }
  PetscFunctionReturn(0);
}

PetscErrorCode MatGetInfo_SeqBAIJ(Mat A, MatInfoType flag, MatInfo *info) {
  Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data;

  PetscFunctionBegin;
  info->block_size   = a->bs2;
  info->nz_allocated = a->bs2 * a->maxnz;
  info->nz_used      = a->bs2 * a->nz;
  info->nz_unneeded  = info->nz_allocated - info->nz_used;
  info->assemblies   = A->num_ass;
  info->mallocs      = A->info.mallocs;
  info->memory       = ((PetscObject)A)->mem;
  if (A->factortype) {
    info->fill_ratio_given  = A->info.fill_ratio_given;
    info->fill_ratio_needed = A->info.fill_ratio_needed;
    info->factor_mallocs    = A->info.factor_mallocs;
  } else {
    info->fill_ratio_given  = 0;
    info->fill_ratio_needed = 0;
    info->factor_mallocs    = 0;
  }
  PetscFunctionReturn(0);
}

PetscErrorCode MatZeroEntries_SeqBAIJ(Mat A) {
  Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data;

  PetscFunctionBegin;
  PetscCall(PetscArrayzero(a->a, a->bs2 * a->i[a->mbs]));
  PetscFunctionReturn(0);
}

PetscErrorCode MatMatMultSymbolic_SeqBAIJ_SeqDense(Mat A, Mat B, PetscReal fill, Mat C) {
  PetscFunctionBegin;
  PetscCall(MatMatMultSymbolic_SeqDense_SeqDense(A, B, 0.0, C));
  C->ops->matmultnumeric = MatMatMultNumeric_SeqBAIJ_SeqDense;
  PetscFunctionReturn(0);
}

PetscErrorCode MatMatMult_SeqBAIJ_1_Private(Mat A, PetscScalar *b, PetscInt bm, PetscScalar *c, PetscInt cm, PetscInt cn) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1;
  const PetscScalar *xb;
  PetscScalar        x1;
  const MatScalar   *v, *vv;
  PetscInt           mbs, i, *idx, *ii, j, *jj, n, k, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = c;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA); /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + n, n, 0, PETSC_PREFETCH_HINT_NTA);   /* Entries for the next row */
    if (usecprow) z = c + ridx[i];
    jj = idx;
    vv = v;
    for (k = 0; k < cn; k++) {
      idx  = jj;
      v    = vv;
      sum1 = 0.0;
      for (j = 0; j < n; j++) {
        xb = b + (*idx++);
        x1 = xb[0 + k * bm];
        sum1 += v[0] * x1;
        v += 1;
      }
      z[0 + k * cm] = sum1;
    }
    if (!usecprow) z += 1;
  }
  PetscFunctionReturn(0);
}

PetscErrorCode MatMatMult_SeqBAIJ_2_Private(Mat A, PetscScalar *b, PetscInt bm, PetscScalar *c, PetscInt cm, PetscInt cn) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2;
  const PetscScalar *xb;
  PetscScalar        x1, x2;
  const MatScalar   *v, *vv;
  PetscInt           mbs, i, *idx, *ii, j, *jj, n, k, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = c;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);       /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 4 * n, 4 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    if (usecprow) z = c + 2 * ridx[i];
    jj = idx;
    vv = v;
    for (k = 0; k < cn; k++) {
      idx  = jj;
      v    = vv;
      sum1 = 0.0;
      sum2 = 0.0;
      for (j = 0; j < n; j++) {
        xb = b + 2 * (*idx++);
        x1 = xb[0 + k * bm];
        x2 = xb[1 + k * bm];
        sum1 += v[0] * x1 + v[2] * x2;
        sum2 += v[1] * x1 + v[3] * x2;
        v += 4;
      }
      z[0 + k * cm] = sum1;
      z[1 + k * cm] = sum2;
    }
    if (!usecprow) z += 2;
  }
  PetscFunctionReturn(0);
}

PetscErrorCode MatMatMult_SeqBAIJ_3_Private(Mat A, PetscScalar *b, PetscInt bm, PetscScalar *c, PetscInt cm, PetscInt cn) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3;
  const PetscScalar *xb;
  PetscScalar        x1, x2, x3;
  const MatScalar   *v, *vv;
  PetscInt           mbs, i, *idx, *ii, j, *jj, n, k, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = c;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);       /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 9 * n, 9 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    if (usecprow) z = c + 3 * ridx[i];
    jj = idx;
    vv = v;
    for (k = 0; k < cn; k++) {
      idx  = jj;
      v    = vv;
      sum1 = 0.0;
      sum2 = 0.0;
      sum3 = 0.0;
      for (j = 0; j < n; j++) {
        xb = b + 3 * (*idx++);
        x1 = xb[0 + k * bm];
        x2 = xb[1 + k * bm];
        x3 = xb[2 + k * bm];
        sum1 += v[0] * x1 + v[3] * x2 + v[6] * x3;
        sum2 += v[1] * x1 + v[4] * x2 + v[7] * x3;
        sum3 += v[2] * x1 + v[5] * x2 + v[8] * x3;
        v += 9;
      }
      z[0 + k * cm] = sum1;
      z[1 + k * cm] = sum2;
      z[2 + k * cm] = sum3;
    }
    if (!usecprow) z += 3;
  }
  PetscFunctionReturn(0);
}

PetscErrorCode MatMatMult_SeqBAIJ_4_Private(Mat A, PetscScalar *b, PetscInt bm, PetscScalar *c, PetscInt cm, PetscInt cn) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4;
  const PetscScalar *xb;
  PetscScalar        x1, x2, x3, x4;
  const MatScalar   *v, *vv;
  PetscInt           mbs, i, *idx, *ii, j, *jj, n, k, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = c;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 16 * n, 16 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    if (usecprow) z = c + 4 * ridx[i];
    jj = idx;
    vv = v;
    for (k = 0; k < cn; k++) {
      idx  = jj;
      v    = vv;
      sum1 = 0.0;
      sum2 = 0.0;
      sum3 = 0.0;
      sum4 = 0.0;
      for (j = 0; j < n; j++) {
        xb = b + 4 * (*idx++);
        x1 = xb[0 + k * bm];
        x2 = xb[1 + k * bm];
        x3 = xb[2 + k * bm];
        x4 = xb[3 + k * bm];
        sum1 += v[0] * x1 + v[4] * x2 + v[8] * x3 + v[12] * x4;
        sum2 += v[1] * x1 + v[5] * x2 + v[9] * x3 + v[13] * x4;
        sum3 += v[2] * x1 + v[6] * x2 + v[10] * x3 + v[14] * x4;
        sum4 += v[3] * x1 + v[7] * x2 + v[11] * x3 + v[15] * x4;
        v += 16;
      }
      z[0 + k * cm] = sum1;
      z[1 + k * cm] = sum2;
      z[2 + k * cm] = sum3;
      z[3 + k * cm] = sum4;
    }
    if (!usecprow) z += 4;
  }
  PetscFunctionReturn(0);
}

PetscErrorCode MatMatMult_SeqBAIJ_5_Private(Mat A, PetscScalar *b, PetscInt bm, PetscScalar *c, PetscInt cm, PetscInt cn) {
  Mat_SeqBAIJ       *a = (Mat_SeqBAIJ *)A->data;
  PetscScalar       *z = NULL, sum1, sum2, sum3, sum4, sum5;
  const PetscScalar *xb;
  PetscScalar        x1, x2, x3, x4, x5;
  const MatScalar   *v, *vv;
  PetscInt           mbs, i, *idx, *ii, j, *jj, n, k, *ridx = NULL;
  PetscBool          usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  idx = a->j;
  v   = a->a;
  if (usecprow) {
    mbs  = a->compressedrow.nrows;
    ii   = a->compressedrow.i;
    ridx = a->compressedrow.rindex;
  } else {
    mbs = a->mbs;
    ii  = a->i;
    z   = c;
  }

  for (i = 0; i < mbs; i++) {
    n = ii[1] - ii[0];
    ii++;
    PetscPrefetchBlock(idx + n, n, 0, PETSC_PREFETCH_HINT_NTA);         /* Indices for the next row (assumes same size as this one) */
    PetscPrefetchBlock(v + 25 * n, 25 * n, 0, PETSC_PREFETCH_HINT_NTA); /* Entries for the next row */
    if (usecprow) z = c + 5 * ridx[i];
    jj = idx;
    vv = v;
    for (k = 0; k < cn; k++) {
      idx  = jj;
      v    = vv;
      sum1 = 0.0;
      sum2 = 0.0;
      sum3 = 0.0;
      sum4 = 0.0;
      sum5 = 0.0;
      for (j = 0; j < n; j++) {
        xb = b + 5 * (*idx++);
        x1 = xb[0 + k * bm];
        x2 = xb[1 + k * bm];
        x3 = xb[2 + k * bm];
        x4 = xb[3 + k * bm];
        x5 = xb[4 + k * bm];
        sum1 += v[0] * x1 + v[5] * x2 + v[10] * x3 + v[15] * x4 + v[20] * x5;
        sum2 += v[1] * x1 + v[6] * x2 + v[11] * x3 + v[16] * x4 + v[21] * x5;
        sum3 += v[2] * x1 + v[7] * x2 + v[12] * x3 + v[17] * x4 + v[22] * x5;
        sum4 += v[3] * x1 + v[8] * x2 + v[13] * x3 + v[18] * x4 + v[23] * x5;
        sum5 += v[4] * x1 + v[9] * x2 + v[14] * x3 + v[19] * x4 + v[24] * x5;
        v += 25;
      }
      z[0 + k * cm] = sum1;
      z[1 + k * cm] = sum2;
      z[2 + k * cm] = sum3;
      z[3 + k * cm] = sum4;
      z[4 + k * cm] = sum5;
    }
    if (!usecprow) z += 5;
  }
  PetscFunctionReturn(0);
}

PetscErrorCode MatMatMultNumeric_SeqBAIJ_SeqDense(Mat A, Mat B, Mat C) {
  Mat_SeqBAIJ     *a  = (Mat_SeqBAIJ *)A->data;
  Mat_SeqDense    *bd = (Mat_SeqDense *)B->data;
  Mat_SeqDense    *cd = (Mat_SeqDense *)C->data;
  PetscInt         cm = cd->lda, cn = B->cmap->n, bm = bd->lda;
  PetscInt         mbs, i, bs = A->rmap->bs, j, n, bs2 = a->bs2;
  PetscBLASInt     bbs, bcn, bbm, bcm;
  PetscScalar     *z = NULL;
  PetscScalar     *c, *b;
  const MatScalar *v;
  const PetscInt  *idx, *ii, *ridx = NULL;
  PetscScalar      _DZero = 0.0, _DOne = 1.0;
  PetscBool        usecprow = a->compressedrow.use;

  PetscFunctionBegin;
  if (!cm || !cn) PetscFunctionReturn(0);
  PetscCheck(B->rmap->n == A->cmap->n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number columns in A %" PetscInt_FMT " not equal rows in B %" PetscInt_FMT, A->cmap->n, B->rmap->n);
  PetscCheck(A->rmap->n == C->rmap->n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number rows in C %" PetscInt_FMT " not equal rows in A %" PetscInt_FMT, C->rmap->n, A->rmap->n);
  PetscCheck(B->cmap->n == C->cmap->n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number columns in B %" PetscInt_FMT " not equal columns in C %" PetscInt_FMT, B->cmap->n, C->cmap->n);
  b = bd->v;
  if (a->nonzerorowcnt != A->rmap->n) { PetscCall(MatZeroEntries(C)); }
  PetscCall(MatDenseGetArray(C, &c));
  switch (bs) {
  case 1: PetscCall(MatMatMult_SeqBAIJ_1_Private(A, b, bm, c, cm, cn)); break;
  case 2: PetscCall(MatMatMult_SeqBAIJ_2_Private(A, b, bm, c, cm, cn)); break;
  case 3: PetscCall(MatMatMult_SeqBAIJ_3_Private(A, b, bm, c, cm, cn)); break;
  case 4: PetscCall(MatMatMult_SeqBAIJ_4_Private(A, b, bm, c, cm, cn)); break;
  case 5: PetscCall(MatMatMult_SeqBAIJ_5_Private(A, b, bm, c, cm, cn)); break;
  default: /* block sizes larger than 5 by 5 are handled by BLAS */
    PetscCall(PetscBLASIntCast(bs, &bbs));
    PetscCall(PetscBLASIntCast(cn, &bcn));
    PetscCall(PetscBLASIntCast(bm, &bbm));
    PetscCall(PetscBLASIntCast(cm, &bcm));
    idx = a->j;
    v   = a->a;
    if (usecprow) {
      mbs  = a->compressedrow.nrows;
      ii   = a->compressedrow.i;
      ridx = a->compressedrow.rindex;
    } else {
      mbs = a->mbs;
      ii  = a->i;
      z   = c;
    }
    for (i = 0; i < mbs; i++) {
      n = ii[1] - ii[0];
      ii++;
      if (usecprow) z = c + bs * ridx[i];
      if (n) {
        PetscCallBLAS("BLASgemm", BLASgemm_("N", "N", &bbs, &bcn, &bbs, &_DOne, v, &bbs, b + bs * (*idx++), &bbm, &_DZero, z, &bcm));
        v += bs2;
      }
      for (j = 1; j < n; j++) {
        PetscCallBLAS("BLASgemm", BLASgemm_("N", "N", &bbs, &bcn, &bbs, &_DOne, v, &bbs, b + bs * (*idx++), &bbm, &_DOne, z, &bcm));
        v += bs2;
      }
      if (!usecprow) z += bs;
    }
  }
  PetscCall(MatDenseRestoreArray(C, &c));
  PetscCall(PetscLogFlops((2.0 * a->nz * bs2 - bs * a->nonzerorowcnt) * cn));
  PetscFunctionReturn(0);
}