xref: /petsc/src/mat/impls/sbaij/seq/sbaijfact12.c (revision e8e8640d1cb9a3a2f50c0c0d7b26e5c4d521e2e4)
1 #include <../src/mat/impls/sbaij/seq/sbaij.h>
2 #include <petsc/private/kernels/blockinvert.h>
3 
4 /*
5       Version for when blocks are 7 by 7 Using natural ordering
6 */
MatCholeskyFactorNumeric_SeqSBAIJ_7_NaturalOrdering(Mat C,Mat A,const MatFactorInfo * info)7 PetscErrorCode MatCholeskyFactorNumeric_SeqSBAIJ_7_NaturalOrdering(Mat C, Mat A, const MatFactorInfo *info)
8 {
9   Mat_SeqSBAIJ *a = (Mat_SeqSBAIJ *)A->data, *b = (Mat_SeqSBAIJ *)C->data;
10   PetscInt      i, j, mbs = a->mbs, *bi = b->i, *bj = b->j;
11   PetscInt     *ai, *aj, k, k1, jmin, jmax, *jl, *il, vj, nexti, ili;
12   MatScalar    *ba = b->a, *aa, *ap, *dk, *uik;
13   MatScalar    *u, *d, *w, *wp, u0, u1, u2, u3, u4, u5, u6, u7, u8, u9, u10, u11, u12;
14   MatScalar     u13, u14, u15, u16, u17, u18, u19, u20, u21, u22, u23, u24, u25, u26, u27;
15   MatScalar     u28, u29, u30, u31, u32, u33, u34, u35, u36, u37, u38, u39, u40, u41;
16   MatScalar     u42, u43, u44, u45, u46, u47, u48;
17   PetscReal     shift = info->shiftamount;
18   PetscBool     allowzeropivot, zeropivotdetected;
19 
20   PetscFunctionBegin;
21   /* initialization */
22   allowzeropivot = PetscNot(A->erroriffailure);
23   PetscCall(PetscCalloc1(49 * mbs, &w));
24   PetscCall(PetscMalloc2(mbs, &il, mbs, &jl));
25   il[0] = 0;
26   for (i = 0; i < mbs; i++) jl[i] = mbs;
27 
28   PetscCall(PetscMalloc2(49, &dk, 49, &uik));
29   ai = a->i;
30   aj = a->j;
31   aa = a->a;
32 
33   /* for each row k */
34   for (k = 0; k < mbs; k++) {
35     /*initialize k-th row with elements nonzero in row k of A */
36     jmin = ai[k];
37     jmax = ai[k + 1];
38     if (jmin < jmax) {
39       ap = aa + jmin * 49;
40       for (j = jmin; j < jmax; j++) {
41         vj = aj[j]; /* block col. index */
42         wp = w + vj * 49;
43         PetscCall(PetscArraycpy(wp, ap, 49));
44         ap += 49;
45       }
46     }
47 
48     /* modify k-th row by adding in those rows i with U(i,k) != 0 */
49     PetscCall(PetscArraycpy(dk, w + k * 49, 49));
50     i = jl[k]; /* first row to be added to k_th row  */
51 
52     while (i < mbs) {
53       nexti = jl[i]; /* next row to be added to k_th row */
54 
55       /* compute multiplier */
56       ili = il[i]; /* index of first nonzero element in U(i,k:bms-1) */
57 
58       /* uik = -inv(Di)*U_bar(i,k) */
59       d = ba + i * 49;
60       u = ba + ili * 49;
61 
62       u0  = u[0];
63       u1  = u[1];
64       u2  = u[2];
65       u3  = u[3];
66       u4  = u[4];
67       u5  = u[5];
68       u6  = u[6];
69       u7  = u[7];
70       u8  = u[8];
71       u9  = u[9];
72       u10 = u[10];
73       u11 = u[11];
74       u12 = u[12];
75       u13 = u[13];
76       u14 = u[14];
77       u15 = u[15];
78       u16 = u[16];
79       u17 = u[17];
80       u18 = u[18];
81       u19 = u[19];
82       u20 = u[20];
83       u21 = u[21];
84       u22 = u[22];
85       u23 = u[23];
86       u24 = u[24];
87       u25 = u[25];
88       u26 = u[26];
89       u27 = u[27];
90       u28 = u[28];
91       u29 = u[29];
92       u30 = u[30];
93       u31 = u[31];
94       u32 = u[32];
95       u33 = u[33];
96       u34 = u[34];
97       u35 = u[35];
98       u36 = u[36];
99       u37 = u[37];
100       u38 = u[38];
101       u39 = u[39];
102       u40 = u[40];
103       u41 = u[41];
104       u42 = u[42];
105       u43 = u[43];
106       u44 = u[44];
107       u45 = u[45];
108       u46 = u[46];
109       u47 = u[47];
110       u48 = u[48];
111 
112       uik[0] = -(d[0] * u0 + d[7] * u1 + d[14] * u2 + d[21] * u3 + d[28] * u4 + d[35] * u5 + d[42] * u6);
113       uik[1] = -(d[1] * u0 + d[8] * u1 + d[15] * u2 + d[22] * u3 + d[29] * u4 + d[36] * u5 + d[43] * u6);
114       uik[2] = -(d[2] * u0 + d[9] * u1 + d[16] * u2 + d[23] * u3 + d[30] * u4 + d[37] * u5 + d[44] * u6);
115       uik[3] = -(d[3] * u0 + d[10] * u1 + d[17] * u2 + d[24] * u3 + d[31] * u4 + d[38] * u5 + d[45] * u6);
116       uik[4] = -(d[4] * u0 + d[11] * u1 + d[18] * u2 + d[25] * u3 + d[32] * u4 + d[39] * u5 + d[46] * u6);
117       uik[5] = -(d[5] * u0 + d[12] * u1 + d[19] * u2 + d[26] * u3 + d[33] * u4 + d[40] * u5 + d[47] * u6);
118       uik[6] = -(d[6] * u0 + d[13] * u1 + d[20] * u2 + d[27] * u3 + d[34] * u4 + d[41] * u5 + d[48] * u6);
119 
120       uik[7]  = -(d[0] * u7 + d[7] * u8 + d[14] * u9 + d[21] * u10 + d[28] * u11 + d[35] * u12 + d[42] * u13);
121       uik[8]  = -(d[1] * u7 + d[8] * u8 + d[15] * u9 + d[22] * u10 + d[29] * u11 + d[36] * u12 + d[43] * u13);
122       uik[9]  = -(d[2] * u7 + d[9] * u8 + d[16] * u9 + d[23] * u10 + d[30] * u11 + d[37] * u12 + d[44] * u13);
123       uik[10] = -(d[3] * u7 + d[10] * u8 + d[17] * u9 + d[24] * u10 + d[31] * u11 + d[38] * u12 + d[45] * u13);
124       uik[11] = -(d[4] * u7 + d[11] * u8 + d[18] * u9 + d[25] * u10 + d[32] * u11 + d[39] * u12 + d[46] * u13);
125       uik[12] = -(d[5] * u7 + d[12] * u8 + d[19] * u9 + d[26] * u10 + d[33] * u11 + d[40] * u12 + d[47] * u13);
126       uik[13] = -(d[6] * u7 + d[13] * u8 + d[20] * u9 + d[27] * u10 + d[34] * u11 + d[41] * u12 + d[48] * u13);
127 
128       uik[14] = -(d[0] * u14 + d[7] * u15 + d[14] * u16 + d[21] * u17 + d[28] * u18 + d[35] * u19 + d[42] * u20);
129       uik[15] = -(d[1] * u14 + d[8] * u15 + d[15] * u16 + d[22] * u17 + d[29] * u18 + d[36] * u19 + d[43] * u20);
130       uik[16] = -(d[2] * u14 + d[9] * u15 + d[16] * u16 + d[23] * u17 + d[30] * u18 + d[37] * u19 + d[44] * u20);
131       uik[17] = -(d[3] * u14 + d[10] * u15 + d[17] * u16 + d[24] * u17 + d[31] * u18 + d[38] * u19 + d[45] * u20);
132       uik[18] = -(d[4] * u14 + d[11] * u15 + d[18] * u16 + d[25] * u17 + d[32] * u18 + d[39] * u19 + d[46] * u20);
133       uik[19] = -(d[5] * u14 + d[12] * u15 + d[19] * u16 + d[26] * u17 + d[33] * u18 + d[40] * u19 + d[47] * u20);
134       uik[20] = -(d[6] * u14 + d[13] * u15 + d[20] * u16 + d[27] * u17 + d[34] * u18 + d[41] * u19 + d[48] * u20);
135 
136       uik[21] = -(d[0] * u21 + d[7] * u22 + d[14] * u23 + d[21] * u24 + d[28] * u25 + d[35] * u26 + d[42] * u27);
137       uik[22] = -(d[1] * u21 + d[8] * u22 + d[15] * u23 + d[22] * u24 + d[29] * u25 + d[36] * u26 + d[43] * u27);
138       uik[23] = -(d[2] * u21 + d[9] * u22 + d[16] * u23 + d[23] * u24 + d[30] * u25 + d[37] * u26 + d[44] * u27);
139       uik[24] = -(d[3] * u21 + d[10] * u22 + d[17] * u23 + d[24] * u24 + d[31] * u25 + d[38] * u26 + d[45] * u27);
140       uik[25] = -(d[4] * u21 + d[11] * u22 + d[18] * u23 + d[25] * u24 + d[32] * u25 + d[39] * u26 + d[46] * u27);
141       uik[26] = -(d[5] * u21 + d[12] * u22 + d[19] * u23 + d[26] * u24 + d[33] * u25 + d[40] * u26 + d[47] * u27);
142       uik[27] = -(d[6] * u21 + d[13] * u22 + d[20] * u23 + d[27] * u24 + d[34] * u25 + d[41] * u26 + d[48] * u27);
143 
144       uik[28] = -(d[0] * u28 + d[7] * u29 + d[14] * u30 + d[21] * u31 + d[28] * u32 + d[35] * u33 + d[42] * u34);
145       uik[29] = -(d[1] * u28 + d[8] * u29 + d[15] * u30 + d[22] * u31 + d[29] * u32 + d[36] * u33 + d[43] * u34);
146       uik[30] = -(d[2] * u28 + d[9] * u29 + d[16] * u30 + d[23] * u31 + d[30] * u32 + d[37] * u33 + d[44] * u34);
147       uik[31] = -(d[3] * u28 + d[10] * u29 + d[17] * u30 + d[24] * u31 + d[31] * u32 + d[38] * u33 + d[45] * u34);
148       uik[32] = -(d[4] * u28 + d[11] * u29 + d[18] * u30 + d[25] * u31 + d[32] * u32 + d[39] * u33 + d[46] * u34);
149       uik[33] = -(d[5] * u28 + d[12] * u29 + d[19] * u30 + d[26] * u31 + d[33] * u32 + d[40] * u33 + d[47] * u34);
150       uik[34] = -(d[6] * u28 + d[13] * u29 + d[20] * u30 + d[27] * u31 + d[34] * u32 + d[41] * u33 + d[48] * u34);
151 
152       uik[35] = -(d[0] * u35 + d[7] * u36 + d[14] * u37 + d[21] * u38 + d[28] * u39 + d[35] * u40 + d[42] * u41);
153       uik[36] = -(d[1] * u35 + d[8] * u36 + d[15] * u37 + d[22] * u38 + d[29] * u39 + d[36] * u40 + d[43] * u41);
154       uik[37] = -(d[2] * u35 + d[9] * u36 + d[16] * u37 + d[23] * u38 + d[30] * u39 + d[37] * u40 + d[44] * u41);
155       uik[38] = -(d[3] * u35 + d[10] * u36 + d[17] * u37 + d[24] * u38 + d[31] * u39 + d[38] * u40 + d[45] * u41);
156       uik[39] = -(d[4] * u35 + d[11] * u36 + d[18] * u37 + d[25] * u38 + d[32] * u39 + d[39] * u40 + d[46] * u41);
157       uik[40] = -(d[5] * u35 + d[12] * u36 + d[19] * u37 + d[26] * u38 + d[33] * u39 + d[40] * u40 + d[47] * u41);
158       uik[41] = -(d[6] * u35 + d[13] * u36 + d[20] * u37 + d[27] * u38 + d[34] * u39 + d[41] * u40 + d[48] * u41);
159 
160       uik[42] = -(d[0] * u42 + d[7] * u43 + d[14] * u44 + d[21] * u45 + d[28] * u46 + d[35] * u47 + d[42] * u48);
161       uik[43] = -(d[1] * u42 + d[8] * u43 + d[15] * u44 + d[22] * u45 + d[29] * u46 + d[36] * u47 + d[43] * u48);
162       uik[44] = -(d[2] * u42 + d[9] * u43 + d[16] * u44 + d[23] * u45 + d[30] * u46 + d[37] * u47 + d[44] * u48);
163       uik[45] = -(d[3] * u42 + d[10] * u43 + d[17] * u44 + d[24] * u45 + d[31] * u46 + d[38] * u47 + d[45] * u48);
164       uik[46] = -(d[4] * u42 + d[11] * u43 + d[18] * u44 + d[25] * u45 + d[32] * u46 + d[39] * u47 + d[46] * u48);
165       uik[47] = -(d[5] * u42 + d[12] * u43 + d[19] * u44 + d[26] * u45 + d[33] * u46 + d[40] * u47 + d[47] * u48);
166       uik[48] = -(d[6] * u42 + d[13] * u43 + d[20] * u44 + d[27] * u45 + d[34] * u46 + d[41] * u47 + d[48] * u48);
167 
168       /* update D(k) += -U(i,k)^T * U_bar(i,k) */
169       dk[0] += uik[0] * u0 + uik[1] * u1 + uik[2] * u2 + uik[3] * u3 + uik[4] * u4 + uik[5] * u5 + uik[6] * u6;
170       dk[1] += uik[7] * u0 + uik[8] * u1 + uik[9] * u2 + uik[10] * u3 + uik[11] * u4 + uik[12] * u5 + uik[13] * u6;
171       dk[2] += uik[14] * u0 + uik[15] * u1 + uik[16] * u2 + uik[17] * u3 + uik[18] * u4 + uik[19] * u5 + uik[20] * u6;
172       dk[3] += uik[21] * u0 + uik[22] * u1 + uik[23] * u2 + uik[24] * u3 + uik[25] * u4 + uik[26] * u5 + uik[27] * u6;
173       dk[4] += uik[28] * u0 + uik[29] * u1 + uik[30] * u2 + uik[31] * u3 + uik[32] * u4 + uik[33] * u5 + uik[34] * u6;
174       dk[5] += uik[35] * u0 + uik[36] * u1 + uik[37] * u2 + uik[38] * u3 + uik[39] * u4 + uik[40] * u5 + uik[41] * u6;
175       dk[6] += uik[42] * u0 + uik[43] * u1 + uik[44] * u2 + uik[45] * u3 + uik[46] * u4 + uik[47] * u5 + uik[48] * u6;
176 
177       dk[7] += uik[0] * u7 + uik[1] * u8 + uik[2] * u9 + uik[3] * u10 + uik[4] * u11 + uik[5] * u12 + uik[6] * u13;
178       dk[8] += uik[7] * u7 + uik[8] * u8 + uik[9] * u9 + uik[10] * u10 + uik[11] * u11 + uik[12] * u12 + uik[13] * u13;
179       dk[9] += uik[14] * u7 + uik[15] * u8 + uik[16] * u9 + uik[17] * u10 + uik[18] * u11 + uik[19] * u12 + uik[20] * u13;
180       dk[10] += uik[21] * u7 + uik[22] * u8 + uik[23] * u9 + uik[24] * u10 + uik[25] * u11 + uik[26] * u12 + uik[27] * u13;
181       dk[11] += uik[28] * u7 + uik[29] * u8 + uik[30] * u9 + uik[31] * u10 + uik[32] * u11 + uik[33] * u12 + uik[34] * u13;
182       dk[12] += uik[35] * u7 + uik[36] * u8 + uik[37] * u9 + uik[38] * u10 + uik[39] * u11 + uik[40] * u12 + uik[41] * u13;
183       dk[13] += uik[42] * u7 + uik[43] * u8 + uik[44] * u9 + uik[45] * u10 + uik[46] * u11 + uik[47] * u12 + uik[48] * u13;
184 
185       dk[14] += uik[0] * u14 + uik[1] * u15 + uik[2] * u16 + uik[3] * u17 + uik[4] * u18 + uik[5] * u19 + uik[6] * u20;
186       dk[15] += uik[7] * u14 + uik[8] * u15 + uik[9] * u16 + uik[10] * u17 + uik[11] * u18 + uik[12] * u19 + uik[13] * u20;
187       dk[16] += uik[14] * u14 + uik[15] * u15 + uik[16] * u16 + uik[17] * u17 + uik[18] * u18 + uik[19] * u19 + uik[20] * u20;
188       dk[17] += uik[21] * u14 + uik[22] * u15 + uik[23] * u16 + uik[24] * u17 + uik[25] * u18 + uik[26] * u19 + uik[27] * u20;
189       dk[18] += uik[28] * u14 + uik[29] * u15 + uik[30] * u16 + uik[31] * u17 + uik[32] * u18 + uik[33] * u19 + uik[34] * u20;
190       dk[19] += uik[35] * u14 + uik[36] * u15 + uik[37] * u16 + uik[38] * u17 + uik[39] * u18 + uik[40] * u19 + uik[41] * u20;
191       dk[20] += uik[42] * u14 + uik[43] * u15 + uik[44] * u16 + uik[45] * u17 + uik[46] * u18 + uik[47] * u19 + uik[48] * u20;
192 
193       dk[21] += uik[0] * u21 + uik[1] * u22 + uik[2] * u23 + uik[3] * u24 + uik[4] * u25 + uik[5] * u26 + uik[6] * u27;
194       dk[22] += uik[7] * u21 + uik[8] * u22 + uik[9] * u23 + uik[10] * u24 + uik[11] * u25 + uik[12] * u26 + uik[13] * u27;
195       dk[23] += uik[14] * u21 + uik[15] * u22 + uik[16] * u23 + uik[17] * u24 + uik[18] * u25 + uik[19] * u26 + uik[20] * u27;
196       dk[24] += uik[21] * u21 + uik[22] * u22 + uik[23] * u23 + uik[24] * u24 + uik[25] * u25 + uik[26] * u26 + uik[27] * u27;
197       dk[25] += uik[28] * u21 + uik[29] * u22 + uik[30] * u23 + uik[31] * u24 + uik[32] * u25 + uik[33] * u26 + uik[34] * u27;
198       dk[26] += uik[35] * u21 + uik[36] * u22 + uik[37] * u23 + uik[38] * u24 + uik[39] * u25 + uik[40] * u26 + uik[41] * u27;
199       dk[27] += uik[42] * u21 + uik[43] * u22 + uik[44] * u23 + uik[45] * u24 + uik[46] * u25 + uik[47] * u26 + uik[48] * u27;
200 
201       dk[28] += uik[0] * u28 + uik[1] * u29 + uik[2] * u30 + uik[3] * u31 + uik[4] * u32 + uik[5] * u33 + uik[6] * u34;
202       dk[29] += uik[7] * u28 + uik[8] * u29 + uik[9] * u30 + uik[10] * u31 + uik[11] * u32 + uik[12] * u33 + uik[13] * u34;
203       dk[30] += uik[14] * u28 + uik[15] * u29 + uik[16] * u30 + uik[17] * u31 + uik[18] * u32 + uik[19] * u33 + uik[20] * u34;
204       dk[31] += uik[21] * u28 + uik[22] * u29 + uik[23] * u30 + uik[24] * u31 + uik[25] * u32 + uik[26] * u33 + uik[27] * u34;
205       dk[32] += uik[28] * u28 + uik[29] * u29 + uik[30] * u30 + uik[31] * u31 + uik[32] * u32 + uik[33] * u33 + uik[34] * u34;
206       dk[33] += uik[35] * u28 + uik[36] * u29 + uik[37] * u30 + uik[38] * u31 + uik[39] * u32 + uik[40] * u33 + uik[41] * u34;
207       dk[34] += uik[42] * u28 + uik[43] * u29 + uik[44] * u30 + uik[45] * u31 + uik[46] * u32 + uik[47] * u33 + uik[48] * u34;
208 
209       dk[35] += uik[0] * u35 + uik[1] * u36 + uik[2] * u37 + uik[3] * u38 + uik[4] * u39 + uik[5] * u40 + uik[6] * u41;
210       dk[36] += uik[7] * u35 + uik[8] * u36 + uik[9] * u37 + uik[10] * u38 + uik[11] * u39 + uik[12] * u40 + uik[13] * u41;
211       dk[37] += uik[14] * u35 + uik[15] * u36 + uik[16] * u37 + uik[17] * u38 + uik[18] * u39 + uik[19] * u40 + uik[20] * u41;
212       dk[38] += uik[21] * u35 + uik[22] * u36 + uik[23] * u37 + uik[24] * u38 + uik[25] * u39 + uik[26] * u40 + uik[27] * u41;
213       dk[39] += uik[28] * u35 + uik[29] * u36 + uik[30] * u37 + uik[31] * u38 + uik[32] * u39 + uik[33] * u40 + uik[34] * u41;
214       dk[40] += uik[35] * u35 + uik[36] * u36 + uik[37] * u37 + uik[38] * u38 + uik[39] * u39 + uik[40] * u40 + uik[41] * u41;
215       dk[41] += uik[42] * u35 + uik[43] * u36 + uik[44] * u37 + uik[45] * u38 + uik[46] * u39 + uik[47] * u40 + uik[48] * u41;
216 
217       dk[42] += uik[0] * u42 + uik[1] * u43 + uik[2] * u44 + uik[3] * u45 + uik[4] * u46 + uik[5] * u47 + uik[6] * u48;
218       dk[43] += uik[7] * u42 + uik[8] * u43 + uik[9] * u44 + uik[10] * u45 + uik[11] * u46 + uik[12] * u47 + uik[13] * u48;
219       dk[44] += uik[14] * u42 + uik[15] * u43 + uik[16] * u44 + uik[17] * u45 + uik[18] * u46 + uik[19] * u47 + uik[20] * u48;
220       dk[45] += uik[21] * u42 + uik[22] * u43 + uik[23] * u44 + uik[24] * u45 + uik[25] * u46 + uik[26] * u47 + uik[27] * u48;
221       dk[46] += uik[28] * u42 + uik[29] * u43 + uik[30] * u44 + uik[31] * u45 + uik[32] * u46 + uik[33] * u47 + uik[34] * u48;
222       dk[47] += uik[35] * u42 + uik[36] * u43 + uik[37] * u44 + uik[38] * u45 + uik[39] * u46 + uik[40] * u47 + uik[41] * u48;
223       dk[48] += uik[42] * u42 + uik[43] * u43 + uik[44] * u44 + uik[45] * u45 + uik[46] * u46 + uik[47] * u47 + uik[48] * u48;
224 
225       PetscCall(PetscLogFlops(343.0 * 4.0));
226 
227       /* update -U(i,k) */
228       PetscCall(PetscArraycpy(ba + ili * 49, uik, 49));
229 
230       /* add multiple of row i to k-th row ... */
231       jmin = ili + 1;
232       jmax = bi[i + 1];
233       if (jmin < jmax) {
234         for (j = jmin; j < jmax; j++) {
235           /* w += -U(i,k)^T * U_bar(i,j) */
236           wp = w + bj[j] * 49;
237           u  = ba + j * 49;
238 
239           u0  = u[0];
240           u1  = u[1];
241           u2  = u[2];
242           u3  = u[3];
243           u4  = u[4];
244           u5  = u[5];
245           u6  = u[6];
246           u7  = u[7];
247           u8  = u[8];
248           u9  = u[9];
249           u10 = u[10];
250           u11 = u[11];
251           u12 = u[12];
252           u13 = u[13];
253           u14 = u[14];
254           u15 = u[15];
255           u16 = u[16];
256           u17 = u[17];
257           u18 = u[18];
258           u19 = u[19];
259           u20 = u[20];
260           u21 = u[21];
261           u22 = u[22];
262           u23 = u[23];
263           u24 = u[24];
264           u25 = u[25];
265           u26 = u[26];
266           u27 = u[27];
267           u28 = u[28];
268           u29 = u[29];
269           u30 = u[30];
270           u31 = u[31];
271           u32 = u[32];
272           u33 = u[33];
273           u34 = u[34];
274           u35 = u[35];
275           u36 = u[36];
276           u37 = u[37];
277           u38 = u[38];
278           u39 = u[39];
279           u40 = u[40];
280           u41 = u[41];
281           u42 = u[42];
282           u43 = u[43];
283           u44 = u[44];
284           u45 = u[45];
285           u46 = u[46];
286           u47 = u[47];
287           u48 = u[48];
288 
289           wp[0] += uik[0] * u0 + uik[1] * u1 + uik[2] * u2 + uik[3] * u3 + uik[4] * u4 + uik[5] * u5 + uik[6] * u6;
290           wp[1] += uik[7] * u0 + uik[8] * u1 + uik[9] * u2 + uik[10] * u3 + uik[11] * u4 + uik[12] * u5 + uik[13] * u6;
291           wp[2] += uik[14] * u0 + uik[15] * u1 + uik[16] * u2 + uik[17] * u3 + uik[18] * u4 + uik[19] * u5 + uik[20] * u6;
292           wp[3] += uik[21] * u0 + uik[22] * u1 + uik[23] * u2 + uik[24] * u3 + uik[25] * u4 + uik[26] * u5 + uik[27] * u6;
293           wp[4] += uik[28] * u0 + uik[29] * u1 + uik[30] * u2 + uik[31] * u3 + uik[32] * u4 + uik[33] * u5 + uik[34] * u6;
294           wp[5] += uik[35] * u0 + uik[36] * u1 + uik[37] * u2 + uik[38] * u3 + uik[39] * u4 + uik[40] * u5 + uik[41] * u6;
295           wp[6] += uik[42] * u0 + uik[43] * u1 + uik[44] * u2 + uik[45] * u3 + uik[46] * u4 + uik[47] * u5 + uik[48] * u6;
296 
297           wp[7] += uik[0] * u7 + uik[1] * u8 + uik[2] * u9 + uik[3] * u10 + uik[4] * u11 + uik[5] * u12 + uik[6] * u13;
298           wp[8] += uik[7] * u7 + uik[8] * u8 + uik[9] * u9 + uik[10] * u10 + uik[11] * u11 + uik[12] * u12 + uik[13] * u13;
299           wp[9] += uik[14] * u7 + uik[15] * u8 + uik[16] * u9 + uik[17] * u10 + uik[18] * u11 + uik[19] * u12 + uik[20] * u13;
300           wp[10] += uik[21] * u7 + uik[22] * u8 + uik[23] * u9 + uik[24] * u10 + uik[25] * u11 + uik[26] * u12 + uik[27] * u13;
301           wp[11] += uik[28] * u7 + uik[29] * u8 + uik[30] * u9 + uik[31] * u10 + uik[32] * u11 + uik[33] * u12 + uik[34] * u13;
302           wp[12] += uik[35] * u7 + uik[36] * u8 + uik[37] * u9 + uik[38] * u10 + uik[39] * u11 + uik[40] * u12 + uik[41] * u13;
303           wp[13] += uik[42] * u7 + uik[43] * u8 + uik[44] * u9 + uik[45] * u10 + uik[46] * u11 + uik[47] * u12 + uik[48] * u13;
304 
305           wp[14] += uik[0] * u14 + uik[1] * u15 + uik[2] * u16 + uik[3] * u17 + uik[4] * u18 + uik[5] * u19 + uik[6] * u20;
306           wp[15] += uik[7] * u14 + uik[8] * u15 + uik[9] * u16 + uik[10] * u17 + uik[11] * u18 + uik[12] * u19 + uik[13] * u20;
307           wp[16] += uik[14] * u14 + uik[15] * u15 + uik[16] * u16 + uik[17] * u17 + uik[18] * u18 + uik[19] * u19 + uik[20] * u20;
308           wp[17] += uik[21] * u14 + uik[22] * u15 + uik[23] * u16 + uik[24] * u17 + uik[25] * u18 + uik[26] * u19 + uik[27] * u20;
309           wp[18] += uik[28] * u14 + uik[29] * u15 + uik[30] * u16 + uik[31] * u17 + uik[32] * u18 + uik[33] * u19 + uik[34] * u20;
310           wp[19] += uik[35] * u14 + uik[36] * u15 + uik[37] * u16 + uik[38] * u17 + uik[39] * u18 + uik[40] * u19 + uik[41] * u20;
311           wp[20] += uik[42] * u14 + uik[43] * u15 + uik[44] * u16 + uik[45] * u17 + uik[46] * u18 + uik[47] * u19 + uik[48] * u20;
312 
313           wp[21] += uik[0] * u21 + uik[1] * u22 + uik[2] * u23 + uik[3] * u24 + uik[4] * u25 + uik[5] * u26 + uik[6] * u27;
314           wp[22] += uik[7] * u21 + uik[8] * u22 + uik[9] * u23 + uik[10] * u24 + uik[11] * u25 + uik[12] * u26 + uik[13] * u27;
315           wp[23] += uik[14] * u21 + uik[15] * u22 + uik[16] * u23 + uik[17] * u24 + uik[18] * u25 + uik[19] * u26 + uik[20] * u27;
316           wp[24] += uik[21] * u21 + uik[22] * u22 + uik[23] * u23 + uik[24] * u24 + uik[25] * u25 + uik[26] * u26 + uik[27] * u27;
317           wp[25] += uik[28] * u21 + uik[29] * u22 + uik[30] * u23 + uik[31] * u24 + uik[32] * u25 + uik[33] * u26 + uik[34] * u27;
318           wp[26] += uik[35] * u21 + uik[36] * u22 + uik[37] * u23 + uik[38] * u24 + uik[39] * u25 + uik[40] * u26 + uik[41] * u27;
319           wp[27] += uik[42] * u21 + uik[43] * u22 + uik[44] * u23 + uik[45] * u24 + uik[46] * u25 + uik[47] * u26 + uik[48] * u27;
320 
321           wp[28] += uik[0] * u28 + uik[1] * u29 + uik[2] * u30 + uik[3] * u31 + uik[4] * u32 + uik[5] * u33 + uik[6] * u34;
322           wp[29] += uik[7] * u28 + uik[8] * u29 + uik[9] * u30 + uik[10] * u31 + uik[11] * u32 + uik[12] * u33 + uik[13] * u34;
323           wp[30] += uik[14] * u28 + uik[15] * u29 + uik[16] * u30 + uik[17] * u31 + uik[18] * u32 + uik[19] * u33 + uik[20] * u34;
324           wp[31] += uik[21] * u28 + uik[22] * u29 + uik[23] * u30 + uik[24] * u31 + uik[25] * u32 + uik[26] * u33 + uik[27] * u34;
325           wp[32] += uik[28] * u28 + uik[29] * u29 + uik[30] * u30 + uik[31] * u31 + uik[32] * u32 + uik[33] * u33 + uik[34] * u34;
326           wp[33] += uik[35] * u28 + uik[36] * u29 + uik[37] * u30 + uik[38] * u31 + uik[39] * u32 + uik[40] * u33 + uik[41] * u34;
327           wp[34] += uik[42] * u28 + uik[43] * u29 + uik[44] * u30 + uik[45] * u31 + uik[46] * u32 + uik[47] * u33 + uik[48] * u34;
328 
329           wp[35] += uik[0] * u35 + uik[1] * u36 + uik[2] * u37 + uik[3] * u38 + uik[4] * u39 + uik[5] * u40 + uik[6] * u41;
330           wp[36] += uik[7] * u35 + uik[8] * u36 + uik[9] * u37 + uik[10] * u38 + uik[11] * u39 + uik[12] * u40 + uik[13] * u41;
331           wp[37] += uik[14] * u35 + uik[15] * u36 + uik[16] * u37 + uik[17] * u38 + uik[18] * u39 + uik[19] * u40 + uik[20] * u41;
332           wp[38] += uik[21] * u35 + uik[22] * u36 + uik[23] * u37 + uik[24] * u38 + uik[25] * u39 + uik[26] * u40 + uik[27] * u41;
333           wp[39] += uik[28] * u35 + uik[29] * u36 + uik[30] * u37 + uik[31] * u38 + uik[32] * u39 + uik[33] * u40 + uik[34] * u41;
334           wp[40] += uik[35] * u35 + uik[36] * u36 + uik[37] * u37 + uik[38] * u38 + uik[39] * u39 + uik[40] * u40 + uik[41] * u41;
335           wp[41] += uik[42] * u35 + uik[43] * u36 + uik[44] * u37 + uik[45] * u38 + uik[46] * u39 + uik[47] * u40 + uik[48] * u41;
336 
337           wp[42] += uik[0] * u42 + uik[1] * u43 + uik[2] * u44 + uik[3] * u45 + uik[4] * u46 + uik[5] * u47 + uik[6] * u48;
338           wp[43] += uik[7] * u42 + uik[8] * u43 + uik[9] * u44 + uik[10] * u45 + uik[11] * u46 + uik[12] * u47 + uik[13] * u48;
339           wp[44] += uik[14] * u42 + uik[15] * u43 + uik[16] * u44 + uik[17] * u45 + uik[18] * u46 + uik[19] * u47 + uik[20] * u48;
340           wp[45] += uik[21] * u42 + uik[22] * u43 + uik[23] * u44 + uik[24] * u45 + uik[25] * u46 + uik[26] * u47 + uik[27] * u48;
341           wp[46] += uik[28] * u42 + uik[29] * u43 + uik[30] * u44 + uik[31] * u45 + uik[32] * u46 + uik[33] * u47 + uik[34] * u48;
342           wp[47] += uik[35] * u42 + uik[36] * u43 + uik[37] * u44 + uik[38] * u45 + uik[39] * u46 + uik[40] * u47 + uik[41] * u48;
343           wp[48] += uik[42] * u42 + uik[43] * u43 + uik[44] * u44 + uik[45] * u45 + uik[46] * u46 + uik[47] * u47 + uik[48] * u48;
344         }
345         PetscCall(PetscLogFlops(2.0 * 343.0 * (jmax - jmin)));
346 
347         /* ... add i to row list for next nonzero entry */
348         il[i] = jmin; /* update il(i) in column k+1, ... mbs-1 */
349         j     = bj[jmin];
350         jl[i] = jl[j];
351         jl[j] = i; /* update jl */
352       }
353       i = nexti;
354     }
355 
356     /* save nonzero entries in k-th row of U ... */
357 
358     /* invert diagonal block */
359     d = ba + k * 49;
360     PetscCall(PetscArraycpy(d, dk, 49));
361     PetscCall(PetscKernel_A_gets_inverse_A_7(d, shift, allowzeropivot, &zeropivotdetected));
362     if (zeropivotdetected) C->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
363 
364     jmin = bi[k];
365     jmax = bi[k + 1];
366     if (jmin < jmax) {
367       for (j = jmin; j < jmax; j++) {
368         vj = bj[j]; /* block col. index of U */
369         u  = ba + j * 49;
370         wp = w + vj * 49;
371         for (k1 = 0; k1 < 49; k1++) {
372           *u++  = *wp;
373           *wp++ = 0.0;
374         }
375       }
376 
377       /* ... add k to row list for first nonzero entry in k-th row */
378       il[k] = jmin;
379       i     = bj[jmin];
380       jl[k] = jl[i];
381       jl[i] = k;
382     }
383   }
384 
385   PetscCall(PetscFree(w));
386   PetscCall(PetscFree2(il, jl));
387   PetscCall(PetscFree2(dk, uik));
388 
389   C->ops->solve          = MatSolve_SeqSBAIJ_7_NaturalOrdering_inplace;
390   C->ops->solvetranspose = MatSolve_SeqSBAIJ_7_NaturalOrdering_inplace;
391   C->ops->forwardsolve   = MatForwardSolve_SeqSBAIJ_7_NaturalOrdering_inplace;
392   C->ops->backwardsolve  = MatBackwardSolve_SeqSBAIJ_7_NaturalOrdering_inplace;
393   C->assembled           = PETSC_TRUE;
394   C->preallocated        = PETSC_TRUE;
395 
396   PetscCall(PetscLogFlops(1.3333 * 343 * b->mbs)); /* from inverting diagonal blocks */
397   PetscFunctionReturn(PETSC_SUCCESS);
398 }
399