xref: /petsc/src/mat/impls/sbaij/seq/sbaijfact6.c (revision 31d78bcd2b98084dc1368b20eb1129c8b9fb39fe)
1 
2 #include <../src/mat/impls/sbaij/seq/sbaij.h>
3 #include <petsc/private/kernels/blockinvert.h>
4 
5 /* Version for when blocks are 4 by 4  */
6 PetscErrorCode MatCholeskyFactorNumeric_SeqSBAIJ_4(Mat C, Mat A, const MatFactorInfo *info)
7 {
8   Mat_SeqSBAIJ   *a = (Mat_SeqSBAIJ *)A->data, *b = (Mat_SeqSBAIJ *)C->data;
9   IS              perm = b->row;
10   const PetscInt *ai, *aj, *perm_ptr, mbs = a->mbs, *bi = b->i, *bj = b->j;
11   PetscInt        i, j, *a2anew, k, k1, jmin, jmax, *jl, *il, vj, nexti, ili;
12   MatScalar      *ba = b->a, *aa, *ap, *dk, *uik;
13   MatScalar      *u, *diag, *rtmp, *rtmp_ptr;
14   PetscBool       pivotinblocks = b->pivotinblocks;
15   PetscReal       shift         = info->shiftamount;
16   PetscBool       allowzeropivot, zeropivotdetected = PETSC_FALSE;
17 
18   PetscFunctionBegin;
19   /* initialization */
20   allowzeropivot = PetscNot(A->erroriffailure);
21   PetscCall(PetscCalloc1(16 * mbs, &rtmp));
22   PetscCall(PetscMalloc2(mbs, &il, mbs, &jl));
23   il[0] = 0;
24   for (i = 0; i < mbs; i++) jl[i] = mbs;
25 
26   PetscCall(PetscMalloc2(16, &dk, 16, &uik));
27   PetscCall(ISGetIndices(perm, &perm_ptr));
28 
29   /* check permutation */
30   if (!a->permute) {
31     ai = a->i;
32     aj = a->j;
33     aa = a->a;
34   } else {
35     ai = a->inew;
36     aj = a->jnew;
37     PetscCall(PetscMalloc1(16 * ai[mbs], &aa));
38     PetscCall(PetscArraycpy(aa, a->a, 16 * ai[mbs]));
39     PetscCall(PetscMalloc1(ai[mbs], &a2anew));
40     PetscCall(PetscArraycpy(a2anew, a->a2anew, ai[mbs]));
41 
42     for (i = 0; i < mbs; i++) {
43       jmin = ai[i];
44       jmax = ai[i + 1];
45       for (j = jmin; j < jmax; j++) {
46         while (a2anew[j] != j) {
47           k         = a2anew[j];
48           a2anew[j] = a2anew[k];
49           a2anew[k] = k;
50           for (k1 = 0; k1 < 16; k1++) {
51             dk[k1]          = aa[k * 16 + k1];
52             aa[k * 16 + k1] = aa[j * 16 + k1];
53             aa[j * 16 + k1] = dk[k1];
54           }
55         }
56         /* transform columnoriented blocks that lie in the lower triangle to roworiented blocks */
57         if (i > aj[j]) {
58           /* printf("change orientation, row: %d, col: %d\n",i,aj[j]); */
59           ap = aa + j * 16;                       /* ptr to the beginning of j-th block of aa */
60           for (k = 0; k < 16; k++) dk[k] = ap[k]; /* dk <- j-th block of aa */
61           for (k = 0; k < 4; k++) {               /* j-th block of aa <- dk^T */
62             for (k1 = 0; k1 < 4; k1++) *ap++ = dk[k + 4 * k1];
63           }
64         }
65       }
66     }
67     PetscCall(PetscFree(a2anew));
68   }
69 
70   /* for each row k */
71   for (k = 0; k < mbs; k++) {
72     /*initialize k-th row with elements nonzero in row perm(k) of A */
73     jmin = ai[perm_ptr[k]];
74     jmax = ai[perm_ptr[k] + 1];
75     if (jmin < jmax) {
76       ap = aa + jmin * 16;
77       for (j = jmin; j < jmax; j++) {
78         vj       = perm_ptr[aj[j]]; /* block col. index */
79         rtmp_ptr = rtmp + vj * 16;
80         for (i = 0; i < 16; i++) *rtmp_ptr++ = *ap++;
81       }
82     }
83 
84     /* modify k-th row by adding in those rows i with U(i,k) != 0 */
85     PetscCall(PetscArraycpy(dk, rtmp + k * 16, 16));
86     i = jl[k]; /* first row to be added to k_th row  */
87 
88     while (i < mbs) {
89       nexti = jl[i]; /* next row to be added to k_th row */
90 
91       /* compute multiplier */
92       ili = il[i]; /* index of first nonzero element in U(i,k:bms-1) */
93 
94       /* uik = -inv(Di)*U_bar(i,k) */
95       diag = ba + i * 16;
96       u    = ba + ili * 16;
97 
98       uik[0] = -(diag[0] * u[0] + diag[4] * u[1] + diag[8] * u[2] + diag[12] * u[3]);
99       uik[1] = -(diag[1] * u[0] + diag[5] * u[1] + diag[9] * u[2] + diag[13] * u[3]);
100       uik[2] = -(diag[2] * u[0] + diag[6] * u[1] + diag[10] * u[2] + diag[14] * u[3]);
101       uik[3] = -(diag[3] * u[0] + diag[7] * u[1] + diag[11] * u[2] + diag[15] * u[3]);
102 
103       uik[4] = -(diag[0] * u[4] + diag[4] * u[5] + diag[8] * u[6] + diag[12] * u[7]);
104       uik[5] = -(diag[1] * u[4] + diag[5] * u[5] + diag[9] * u[6] + diag[13] * u[7]);
105       uik[6] = -(diag[2] * u[4] + diag[6] * u[5] + diag[10] * u[6] + diag[14] * u[7]);
106       uik[7] = -(diag[3] * u[4] + diag[7] * u[5] + diag[11] * u[6] + diag[15] * u[7]);
107 
108       uik[8]  = -(diag[0] * u[8] + diag[4] * u[9] + diag[8] * u[10] + diag[12] * u[11]);
109       uik[9]  = -(diag[1] * u[8] + diag[5] * u[9] + diag[9] * u[10] + diag[13] * u[11]);
110       uik[10] = -(diag[2] * u[8] + diag[6] * u[9] + diag[10] * u[10] + diag[14] * u[11]);
111       uik[11] = -(diag[3] * u[8] + diag[7] * u[9] + diag[11] * u[10] + diag[15] * u[11]);
112 
113       uik[12] = -(diag[0] * u[12] + diag[4] * u[13] + diag[8] * u[14] + diag[12] * u[15]);
114       uik[13] = -(diag[1] * u[12] + diag[5] * u[13] + diag[9] * u[14] + diag[13] * u[15]);
115       uik[14] = -(diag[2] * u[12] + diag[6] * u[13] + diag[10] * u[14] + diag[14] * u[15]);
116       uik[15] = -(diag[3] * u[12] + diag[7] * u[13] + diag[11] * u[14] + diag[15] * u[15]);
117 
118       /* update D(k) += -U(i,k)^T * U_bar(i,k) */
119       dk[0] += uik[0] * u[0] + uik[1] * u[1] + uik[2] * u[2] + uik[3] * u[3];
120       dk[1] += uik[4] * u[0] + uik[5] * u[1] + uik[6] * u[2] + uik[7] * u[3];
121       dk[2] += uik[8] * u[0] + uik[9] * u[1] + uik[10] * u[2] + uik[11] * u[3];
122       dk[3] += uik[12] * u[0] + uik[13] * u[1] + uik[14] * u[2] + uik[15] * u[3];
123 
124       dk[4] += uik[0] * u[4] + uik[1] * u[5] + uik[2] * u[6] + uik[3] * u[7];
125       dk[5] += uik[4] * u[4] + uik[5] * u[5] + uik[6] * u[6] + uik[7] * u[7];
126       dk[6] += uik[8] * u[4] + uik[9] * u[5] + uik[10] * u[6] + uik[11] * u[7];
127       dk[7] += uik[12] * u[4] + uik[13] * u[5] + uik[14] * u[6] + uik[15] * u[7];
128 
129       dk[8] += uik[0] * u[8] + uik[1] * u[9] + uik[2] * u[10] + uik[3] * u[11];
130       dk[9] += uik[4] * u[8] + uik[5] * u[9] + uik[6] * u[10] + uik[7] * u[11];
131       dk[10] += uik[8] * u[8] + uik[9] * u[9] + uik[10] * u[10] + uik[11] * u[11];
132       dk[11] += uik[12] * u[8] + uik[13] * u[9] + uik[14] * u[10] + uik[15] * u[11];
133 
134       dk[12] += uik[0] * u[12] + uik[1] * u[13] + uik[2] * u[14] + uik[3] * u[15];
135       dk[13] += uik[4] * u[12] + uik[5] * u[13] + uik[6] * u[14] + uik[7] * u[15];
136       dk[14] += uik[8] * u[12] + uik[9] * u[13] + uik[10] * u[14] + uik[11] * u[15];
137       dk[15] += uik[12] * u[12] + uik[13] * u[13] + uik[14] * u[14] + uik[15] * u[15];
138 
139       PetscCall(PetscLogFlops(64.0 * 4.0));
140 
141       /* update -U(i,k) */
142       PetscCall(PetscArraycpy(ba + ili * 16, uik, 16));
143 
144       /* add multiple of row i to k-th row ... */
145       jmin = ili + 1;
146       jmax = bi[i + 1];
147       if (jmin < jmax) {
148         for (j = jmin; j < jmax; j++) {
149           /* rtmp += -U(i,k)^T * U_bar(i,j) */
150           rtmp_ptr = rtmp + bj[j] * 16;
151           u        = ba + j * 16;
152           rtmp_ptr[0] += uik[0] * u[0] + uik[1] * u[1] + uik[2] * u[2] + uik[3] * u[3];
153           rtmp_ptr[1] += uik[4] * u[0] + uik[5] * u[1] + uik[6] * u[2] + uik[7] * u[3];
154           rtmp_ptr[2] += uik[8] * u[0] + uik[9] * u[1] + uik[10] * u[2] + uik[11] * u[3];
155           rtmp_ptr[3] += uik[12] * u[0] + uik[13] * u[1] + uik[14] * u[2] + uik[15] * u[3];
156 
157           rtmp_ptr[4] += uik[0] * u[4] + uik[1] * u[5] + uik[2] * u[6] + uik[3] * u[7];
158           rtmp_ptr[5] += uik[4] * u[4] + uik[5] * u[5] + uik[6] * u[6] + uik[7] * u[7];
159           rtmp_ptr[6] += uik[8] * u[4] + uik[9] * u[5] + uik[10] * u[6] + uik[11] * u[7];
160           rtmp_ptr[7] += uik[12] * u[4] + uik[13] * u[5] + uik[14] * u[6] + uik[15] * u[7];
161 
162           rtmp_ptr[8] += uik[0] * u[8] + uik[1] * u[9] + uik[2] * u[10] + uik[3] * u[11];
163           rtmp_ptr[9] += uik[4] * u[8] + uik[5] * u[9] + uik[6] * u[10] + uik[7] * u[11];
164           rtmp_ptr[10] += uik[8] * u[8] + uik[9] * u[9] + uik[10] * u[10] + uik[11] * u[11];
165           rtmp_ptr[11] += uik[12] * u[8] + uik[13] * u[9] + uik[14] * u[10] + uik[15] * u[11];
166 
167           rtmp_ptr[12] += uik[0] * u[12] + uik[1] * u[13] + uik[2] * u[14] + uik[3] * u[15];
168           rtmp_ptr[13] += uik[4] * u[12] + uik[5] * u[13] + uik[6] * u[14] + uik[7] * u[15];
169           rtmp_ptr[14] += uik[8] * u[12] + uik[9] * u[13] + uik[10] * u[14] + uik[11] * u[15];
170           rtmp_ptr[15] += uik[12] * u[12] + uik[13] * u[13] + uik[14] * u[14] + uik[15] * u[15];
171         }
172         PetscCall(PetscLogFlops(2.0 * 64.0 * (jmax - jmin)));
173 
174         /* ... add i to row list for next nonzero entry */
175         il[i] = jmin; /* update il(i) in column k+1, ... mbs-1 */
176         j     = bj[jmin];
177         jl[i] = jl[j];
178         jl[j] = i; /* update jl */
179       }
180       i = nexti;
181     }
182 
183     /* save nonzero entries in k-th row of U ... */
184 
185     /* invert diagonal block */
186     diag = ba + k * 16;
187     PetscCall(PetscArraycpy(diag, dk, 16));
188 
189     if (pivotinblocks) {
190       PetscCall(PetscKernel_A_gets_inverse_A_4(diag, shift, allowzeropivot, &zeropivotdetected));
191       if (zeropivotdetected) C->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
192     } else {
193       PetscCall(PetscKernel_A_gets_inverse_A_4_nopivot(diag));
194     }
195 
196     jmin = bi[k];
197     jmax = bi[k + 1];
198     if (jmin < jmax) {
199       for (j = jmin; j < jmax; j++) {
200         vj       = bj[j]; /* block col. index of U */
201         u        = ba + j * 16;
202         rtmp_ptr = rtmp + vj * 16;
203         for (k1 = 0; k1 < 16; k1++) {
204           *u++        = *rtmp_ptr;
205           *rtmp_ptr++ = 0.0;
206         }
207       }
208 
209       /* ... add k to row list for first nonzero entry in k-th row */
210       il[k] = jmin;
211       i     = bj[jmin];
212       jl[k] = jl[i];
213       jl[i] = k;
214     }
215   }
216 
217   PetscCall(PetscFree(rtmp));
218   PetscCall(PetscFree2(il, jl));
219   PetscCall(PetscFree2(dk, uik));
220   if (a->permute) PetscCall(PetscFree(aa));
221 
222   PetscCall(ISRestoreIndices(perm, &perm_ptr));
223 
224   C->ops->solve          = MatSolve_SeqSBAIJ_4_inplace;
225   C->ops->solvetranspose = MatSolve_SeqSBAIJ_4_inplace;
226   C->assembled           = PETSC_TRUE;
227   C->preallocated        = PETSC_TRUE;
228 
229   PetscCall(PetscLogFlops(1.3333 * 64 * b->mbs)); /* from inverting diagonal blocks */
230   PetscFunctionReturn(PETSC_SUCCESS);
231 }
232