1 2 #include "src/mat/impls/baij/seq/baij.h" 3 #include "src/inline/spops.h" 4 #include "src/mat/impls/sbaij/seq/sbaij.h" 5 #include "petscsys.h" 6 7 /* 8 This function is used before applying a 9 symmetric reordering to matrix A that is 10 in SBAIJ format. 11 12 The permutation is assumed to be symmetric, i.e., 13 P = P^T (= inv(P)), 14 so the permuted matrix P*A*inv(P)=P*A*P^T is ensured to be symmetric. 15 16 The function is modified from sro.f of YSMP. The description from YSMP: 17 C THE NONZERO ENTRIES OF THE MATRIX M ARE ASSUMED TO BE STORED 18 C SYMMETRICALLY IN (IA,JA,A) FORMAT (I.E., NOT BOTH M(I,J) AND M(J,I) 19 C ARE STORED IF I NE J). 20 C 21 C SRO DOES NOT REARRANGE THE ORDER OF THE ROWS, BUT DOES MOVE 22 C NONZEROES FROM ONE ROW TO ANOTHER TO ENSURE THAT IF M(I,J) WILL BE 23 C IN THE UPPER TRIANGLE OF M WITH RESPECT TO THE NEW ORDERING, THEN 24 C M(I,J) IS STORED IN ROW I (AND THUS M(J,I) IS NOT STORED); WHEREAS 25 C IF M(I,J) WILL BE IN THE STRICT LOWER TRIANGLE OF M, THEN M(J,I) IS 26 C STORED IN ROW J (AND THUS M(I,J) IS NOT STORED). 27 28 29 -- output: new index set (inew, jnew) for A and a map a2anew that maps 30 values a to anew, such that all 31 nonzero A_(perm(i),iperm(k)) will be stored in the upper triangle. 32 Note: matrix A is not permuted by this function! 33 */ 34 #undef __FUNCT__ 35 #define __FUNCT__ "MatReorderingSeqSBAIJ" 36 int MatReorderingSeqSBAIJ(Mat A,IS perm) 37 { 38 Mat_SeqSBAIJ *a=(Mat_SeqSBAIJ *)A->data; 39 int *r,ierr,i,mbs=a->mbs,*rip,*riip; 40 int *ai,*aj; 41 int *nzr,nz,jmin,jmax,j,k,ajk,len; 42 IS iperm; /* inverse of perm */ 43 44 PetscFunctionBegin; 45 if (!mbs) PetscFunctionReturn(0); 46 ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr); 47 ierr = ISInvertPermutation(perm,PETSC_DECIDE,&iperm);CHKERRQ(ierr); 48 ierr = ISGetIndices(iperm,&riip);CHKERRQ(ierr); 49 50 for (i=0; i<mbs; i++) { 51 if (rip[i] != riip[i]) SETERRQ(1,"Non-symm. permutation, use symm. permutation or general matrix format"); 52 } 53 ierr = ISRestoreIndices(iperm,&riip);CHKERRQ(ierr); 54 ierr = ISDestroy(iperm);CHKERRQ(ierr); 55 56 if (!a->inew){ 57 len = (mbs+1 + 2*(a->i[mbs]))*sizeof(int); 58 ierr = PetscMalloc(len,&ai);CHKERRQ(ierr); 59 aj = ai + mbs+1; 60 } else { 61 ai = a->inew; aj = a->jnew; 62 } 63 ierr = PetscMemcpy(ai,a->i,(mbs+1)*sizeof(int));CHKERRQ(ierr); 64 ierr = PetscMemcpy(aj,a->j,(a->i[mbs])*sizeof(int));CHKERRQ(ierr); 65 66 /* 67 Phase 1: Find row index r in which to store each nonzero. 68 Initialize count of nonzeros to be stored in each row (nzr). 69 At the end of this phase, a nonzero a(*,*)=a(r(),aj()) 70 s.t. a(perm(r),perm(aj)) will fall into upper triangle part. 71 */ 72 73 ierr = PetscMalloc(mbs*sizeof(int),&nzr);CHKERRQ(ierr); 74 ierr = PetscMalloc(ai[mbs]*sizeof(int),&r);CHKERRQ(ierr); 75 for (i=0; i<mbs; i++) nzr[i] = 0; 76 for (i=0; i<ai[mbs]; i++) r[i] = 0; 77 78 /* for each nonzero element */ 79 for (i=0; i<mbs; i++){ 80 nz = ai[i+1] - ai[i]; 81 j = ai[i]; 82 /* printf("nz = %d, j=%d\n",nz,j); */ 83 while (nz--){ 84 /* --- find row (=r[j]) and column (=aj[j]) in which to store a[j] ...*/ 85 k = aj[j]; /* col. index */ 86 /* printf("nz = %d, k=%d\n", nz,k); */ 87 /* for entry that will be permuted into lower triangle, swap row and col. index */ 88 if (rip[k] < rip[i]) aj[j] = i; 89 else k = i; 90 91 r[j] = k; j++; 92 nzr[k] ++; /* increment count of nonzeros in that row */ 93 } 94 } 95 96 /* Phase 2: Find new ai and permutation to apply to (aj,a). 97 Determine pointers (r) to delimit rows in permuted (aj,a). 98 Note: r is different from r used in phase 1. 99 At the end of this phase, (aj[j],a[j]) will be stored in 100 (aj[r(j)],a[r(j)]). 101 */ 102 for (i=0; i<mbs; i++){ 103 ai[i+1] = ai[i] + nzr[i]; 104 nzr[i] = ai[i+1]; 105 } 106 107 /* determine where each (aj[j], a[j]) is stored in new (aj,a) 108 for each nonzero element (in reverse order) */ 109 jmin = ai[0]; jmax = ai[mbs]; 110 nz = jmax - jmin; 111 j = jmax-1; 112 while (nz--){ 113 i = r[j]; /* row value */ 114 if (aj[j] == i) r[j] = ai[i]; /* put diagonal nonzero at beginning of row */ 115 else { /* put off-diagonal nonzero in last unused location in row */ 116 nzr[i]--; r[j] = nzr[i]; 117 } 118 j--; 119 } 120 121 a->a2anew = aj + ai[mbs]; 122 ierr = PetscMemcpy(a->a2anew,r,ai[mbs]*sizeof(int));CHKERRQ(ierr); 123 124 /* Phase 3: permute (aj,a) to upper triangular form (wrt new ordering) */ 125 for (j=jmin; j<jmax; j++){ 126 while (r[j] != j){ 127 k = r[j]; r[j] = r[k]; r[k] = k; 128 ajk = aj[k]; aj[k] = aj[j]; aj[j] = ajk; 129 /* ak = aa[k]; aa[k] = aa[j]; aa[j] = ak; */ 130 } 131 } 132 ierr= ISRestoreIndices(perm,&rip);CHKERRQ(ierr); 133 134 a->inew = ai; 135 a->jnew = aj; 136 137 if (a->row) { 138 ierr = ISDestroy(a->row);CHKERRQ(ierr); 139 } 140 if (a->icol) { 141 ierr = ISDestroy(a->icol);CHKERRQ(ierr); 142 } 143 a->row = perm; 144 a->icol = perm; 145 ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr); 146 ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr); 147 148 ierr = PetscFree(nzr);CHKERRQ(ierr); 149 ierr = PetscFree(r);CHKERRQ(ierr); 150 151 PetscFunctionReturn(0); 152 } 153 154 155