Actual source code: pbjacobi.c
petsc-3.13.6 2020-09-29
2: /*
3: Include files needed for the PBJacobi preconditioner:
4: pcimpl.h - private include file intended for use by all preconditioners
5: */
7: #include <petsc/private/pcimpl.h>
9: /*
10: Private context (data structure) for the PBJacobi preconditioner.
11: */
12: typedef struct {
13: const MatScalar *diag;
14: PetscInt bs,mbs;
15: } PC_PBJacobi;
18: static PetscErrorCode PCApply_PBJacobi_1(PC pc,Vec x,Vec y)
19: {
20: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
21: PetscErrorCode ierr;
22: PetscInt i,m = jac->mbs;
23: const MatScalar *diag = jac->diag;
24: const PetscScalar *xx;
25: PetscScalar *yy;
28: VecGetArrayRead(x,&xx);
29: VecGetArray(y,&yy);
30: for (i=0; i<m; i++) yy[i] = diag[i]*xx[i];
31: VecRestoreArrayRead(x,&xx);
32: VecRestoreArray(y,&yy);
33: PetscLogFlops(m);
34: return(0);
35: }
37: static PetscErrorCode PCApply_PBJacobi_2(PC pc,Vec x,Vec y)
38: {
39: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
40: PetscErrorCode ierr;
41: PetscInt i,m = jac->mbs;
42: const MatScalar *diag = jac->diag;
43: PetscScalar x0,x1,*yy;
44: const PetscScalar *xx;
47: VecGetArrayRead(x,&xx);
48: VecGetArray(y,&yy);
49: for (i=0; i<m; i++) {
50: x0 = xx[2*i]; x1 = xx[2*i+1];
51: yy[2*i] = diag[0]*x0 + diag[2]*x1;
52: yy[2*i+1] = diag[1]*x0 + diag[3]*x1;
53: diag += 4;
54: }
55: VecRestoreArrayRead(x,&xx);
56: VecRestoreArray(y,&yy);
57: PetscLogFlops(6.0*m);
58: return(0);
59: }
60: static PetscErrorCode PCApply_PBJacobi_3(PC pc,Vec x,Vec y)
61: {
62: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
63: PetscErrorCode ierr;
64: PetscInt i,m = jac->mbs;
65: const MatScalar *diag = jac->diag;
66: PetscScalar x0,x1,x2,*yy;
67: const PetscScalar *xx;
70: VecGetArrayRead(x,&xx);
71: VecGetArray(y,&yy);
72: for (i=0; i<m; i++) {
73: x0 = xx[3*i]; x1 = xx[3*i+1]; x2 = xx[3*i+2];
75: yy[3*i] = diag[0]*x0 + diag[3]*x1 + diag[6]*x2;
76: yy[3*i+1] = diag[1]*x0 + diag[4]*x1 + diag[7]*x2;
77: yy[3*i+2] = diag[2]*x0 + diag[5]*x1 + diag[8]*x2;
78: diag += 9;
79: }
80: VecRestoreArrayRead(x,&xx);
81: VecRestoreArray(y,&yy);
82: PetscLogFlops(15.0*m);
83: return(0);
84: }
85: static PetscErrorCode PCApply_PBJacobi_4(PC pc,Vec x,Vec y)
86: {
87: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
88: PetscErrorCode ierr;
89: PetscInt i,m = jac->mbs;
90: const MatScalar *diag = jac->diag;
91: PetscScalar x0,x1,x2,x3,*yy;
92: const PetscScalar *xx;
95: VecGetArrayRead(x,&xx);
96: VecGetArray(y,&yy);
97: for (i=0; i<m; i++) {
98: x0 = xx[4*i]; x1 = xx[4*i+1]; x2 = xx[4*i+2]; x3 = xx[4*i+3];
100: yy[4*i] = diag[0]*x0 + diag[4]*x1 + diag[8]*x2 + diag[12]*x3;
101: yy[4*i+1] = diag[1]*x0 + diag[5]*x1 + diag[9]*x2 + diag[13]*x3;
102: yy[4*i+2] = diag[2]*x0 + diag[6]*x1 + diag[10]*x2 + diag[14]*x3;
103: yy[4*i+3] = diag[3]*x0 + diag[7]*x1 + diag[11]*x2 + diag[15]*x3;
104: diag += 16;
105: }
106: VecRestoreArrayRead(x,&xx);
107: VecRestoreArray(y,&yy);
108: PetscLogFlops(28.0*m);
109: return(0);
110: }
111: static PetscErrorCode PCApply_PBJacobi_5(PC pc,Vec x,Vec y)
112: {
113: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
114: PetscErrorCode ierr;
115: PetscInt i,m = jac->mbs;
116: const MatScalar *diag = jac->diag;
117: PetscScalar x0,x1,x2,x3,x4,*yy;
118: const PetscScalar *xx;
121: VecGetArrayRead(x,&xx);
122: VecGetArray(y,&yy);
123: for (i=0; i<m; i++) {
124: x0 = xx[5*i]; x1 = xx[5*i+1]; x2 = xx[5*i+2]; x3 = xx[5*i+3]; x4 = xx[5*i+4];
126: yy[5*i] = diag[0]*x0 + diag[5]*x1 + diag[10]*x2 + diag[15]*x3 + diag[20]*x4;
127: yy[5*i+1] = diag[1]*x0 + diag[6]*x1 + diag[11]*x2 + diag[16]*x3 + diag[21]*x4;
128: yy[5*i+2] = diag[2]*x0 + diag[7]*x1 + diag[12]*x2 + diag[17]*x3 + diag[22]*x4;
129: yy[5*i+3] = diag[3]*x0 + diag[8]*x1 + diag[13]*x2 + diag[18]*x3 + diag[23]*x4;
130: yy[5*i+4] = diag[4]*x0 + diag[9]*x1 + diag[14]*x2 + diag[19]*x3 + diag[24]*x4;
131: diag += 25;
132: }
133: VecRestoreArrayRead(x,&xx);
134: VecRestoreArray(y,&yy);
135: PetscLogFlops(45.0*m);
136: return(0);
137: }
138: static PetscErrorCode PCApply_PBJacobi_6(PC pc,Vec x,Vec y)
139: {
140: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
141: PetscErrorCode ierr;
142: PetscInt i,m = jac->mbs;
143: const MatScalar *diag = jac->diag;
144: PetscScalar x0,x1,x2,x3,x4,x5,*yy;
145: const PetscScalar *xx;
148: VecGetArrayRead(x,&xx);
149: VecGetArray(y,&yy);
150: for (i=0; i<m; i++) {
151: x0 = xx[6*i]; x1 = xx[6*i+1]; x2 = xx[6*i+2]; x3 = xx[6*i+3]; x4 = xx[6*i+4]; x5 = xx[6*i+5];
153: yy[6*i] = diag[0]*x0 + diag[6]*x1 + diag[12]*x2 + diag[18]*x3 + diag[24]*x4 + diag[30]*x5;
154: yy[6*i+1] = diag[1]*x0 + diag[7]*x1 + diag[13]*x2 + diag[19]*x3 + diag[25]*x4 + diag[31]*x5;
155: yy[6*i+2] = diag[2]*x0 + diag[8]*x1 + diag[14]*x2 + diag[20]*x3 + diag[26]*x4 + diag[32]*x5;
156: yy[6*i+3] = diag[3]*x0 + diag[9]*x1 + diag[15]*x2 + diag[21]*x3 + diag[27]*x4 + diag[33]*x5;
157: yy[6*i+4] = diag[4]*x0 + diag[10]*x1 + diag[16]*x2 + diag[22]*x3 + diag[28]*x4 + diag[34]*x5;
158: yy[6*i+5] = diag[5]*x0 + diag[11]*x1 + diag[17]*x2 + diag[23]*x3 + diag[29]*x4 + diag[35]*x5;
159: diag += 36;
160: }
161: VecRestoreArrayRead(x,&xx);
162: VecRestoreArray(y,&yy);
163: PetscLogFlops(66.0*m);
164: return(0);
165: }
166: static PetscErrorCode PCApply_PBJacobi_7(PC pc,Vec x,Vec y)
167: {
168: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
169: PetscErrorCode ierr;
170: PetscInt i,m = jac->mbs;
171: const MatScalar *diag = jac->diag;
172: PetscScalar x0,x1,x2,x3,x4,x5,x6,*yy;
173: const PetscScalar *xx;
176: VecGetArrayRead(x,&xx);
177: VecGetArray(y,&yy);
178: for (i=0; i<m; i++) {
179: x0 = xx[7*i]; x1 = xx[7*i+1]; x2 = xx[7*i+2]; x3 = xx[7*i+3]; x4 = xx[7*i+4]; x5 = xx[7*i+5]; x6 = xx[7*i+6];
181: yy[7*i] = diag[0]*x0 + diag[7]*x1 + diag[14]*x2 + diag[21]*x3 + diag[28]*x4 + diag[35]*x5 + diag[42]*x6;
182: yy[7*i+1] = diag[1]*x0 + diag[8]*x1 + diag[15]*x2 + diag[22]*x3 + diag[29]*x4 + diag[36]*x5 + diag[43]*x6;
183: yy[7*i+2] = diag[2]*x0 + diag[9]*x1 + diag[16]*x2 + diag[23]*x3 + diag[30]*x4 + diag[37]*x5 + diag[44]*x6;
184: yy[7*i+3] = diag[3]*x0 + diag[10]*x1 + diag[17]*x2 + diag[24]*x3 + diag[31]*x4 + diag[38]*x5 + diag[45]*x6;
185: yy[7*i+4] = diag[4]*x0 + diag[11]*x1 + diag[18]*x2 + diag[25]*x3 + diag[32]*x4 + diag[39]*x5 + diag[46]*x6;
186: yy[7*i+5] = diag[5]*x0 + diag[12]*x1 + diag[19]*x2 + diag[26]*x3 + diag[33]*x4 + diag[40]*x5 + diag[47]*x6;
187: yy[7*i+6] = diag[6]*x0 + diag[13]*x1 + diag[20]*x2 + diag[27]*x3 + diag[34]*x4 + diag[41]*x5 + diag[48]*x6;
188: diag += 49;
189: }
190: VecRestoreArrayRead(x,&xx);
191: VecRestoreArray(y,&yy);
192: PetscLogFlops(91.0*m); /* 2*bs2 - bs */
193: return(0);
194: }
195: static PetscErrorCode PCApply_PBJacobi_N(PC pc,Vec x,Vec y)
196: {
197: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
198: PetscErrorCode ierr;
199: PetscInt i,ib,jb;
200: const PetscInt m = jac->mbs;
201: const PetscInt bs = jac->bs;
202: const MatScalar *diag = jac->diag;
203: PetscScalar *yy;
204: const PetscScalar *xx;
207: VecGetArrayRead(x,&xx);
208: VecGetArray(y,&yy);
209: for (i=0; i<m; i++) {
210: for (ib=0; ib<bs; ib++){
211: PetscScalar rowsum = 0;
212: for (jb=0; jb<bs; jb++){
213: rowsum += diag[ib+jb*bs] * xx[bs*i+jb];
214: }
215: yy[bs*i+ib] = rowsum;
216: }
217: diag += bs*bs;
218: }
219: VecRestoreArrayRead(x,&xx);
220: VecRestoreArray(y,&yy);
221: PetscLogFlops((2.0*bs*bs-bs)*m); /* 2*bs2 - bs */
222: return(0);
223: }
225: static PetscErrorCode PCApplyTranspose_PBJacobi_N(PC pc,Vec x,Vec y)
226: {
227: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
228: PetscErrorCode ierr;
229: PetscInt i,j,k,m = jac->mbs,bs=jac->bs;
230: const MatScalar *diag = jac->diag;
231: const PetscScalar *xx;
232: PetscScalar *yy;
235: VecGetArrayRead(x,&xx);
236: VecGetArray(y,&yy);
237: for (i=0; i<m; i++) {
238: for (j=0; j<bs; j++) yy[i*bs+j] = 0.;
239: for (j=0; j<bs; j++) {
240: for (k=0; k<bs; k++) {
241: yy[i*bs+k] += diag[k*bs+j]*xx[i*bs+j];
242: }
243: }
244: diag += bs*bs;
245: }
246: VecRestoreArrayRead(x,&xx);
247: VecRestoreArray(y,&yy);
248: PetscLogFlops(m*bs*(2*bs-1));
249: return(0);
250: }
252: /* -------------------------------------------------------------------------- */
253: static PetscErrorCode PCSetUp_PBJacobi(PC pc)
254: {
255: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
257: Mat A = pc->pmat;
258: MatFactorError err;
259: PetscInt nlocal;
260:
262: MatInvertBlockDiagonal(A,&jac->diag);
263: MatFactorGetError(A,&err);
264: if (err) pc->failedreason = (PCFailedReason)err;
265:
266: MatGetBlockSize(A,&jac->bs);
267: MatGetLocalSize(A,&nlocal,NULL);
268: jac->mbs = nlocal/jac->bs;
269: switch (jac->bs) {
270: case 1:
271: pc->ops->apply = PCApply_PBJacobi_1;
272: break;
273: case 2:
274: pc->ops->apply = PCApply_PBJacobi_2;
275: break;
276: case 3:
277: pc->ops->apply = PCApply_PBJacobi_3;
278: break;
279: case 4:
280: pc->ops->apply = PCApply_PBJacobi_4;
281: break;
282: case 5:
283: pc->ops->apply = PCApply_PBJacobi_5;
284: break;
285: case 6:
286: pc->ops->apply = PCApply_PBJacobi_6;
287: break;
288: case 7:
289: pc->ops->apply = PCApply_PBJacobi_7;
290: break;
291: default:
292: pc->ops->apply = PCApply_PBJacobi_N;
293: break;
294: }
295: pc->ops->applytranspose = PCApplyTranspose_PBJacobi_N;
296: return(0);
297: }
298: /* -------------------------------------------------------------------------- */
299: static PetscErrorCode PCDestroy_PBJacobi(PC pc)
300: {
304: /*
305: Free the private data structure that was hanging off the PC
306: */
307: PetscFree(pc->data);
308: return(0);
309: }
311: static PetscErrorCode PCView_PBJacobi(PC pc,PetscViewer viewer)
312: {
314: PC_PBJacobi *jac = (PC_PBJacobi*)pc->data;
315: PetscBool iascii;
318: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
319: if (iascii) {
320: PetscViewerASCIIPrintf(viewer," point-block size %D\n",jac->bs);
321: }
322: return(0);
323: }
325: /* -------------------------------------------------------------------------- */
326: /*MC
327: PCPBJACOBI - Point block Jacobi preconditioner
330: Notes:
331: See PCJACOBI for point Jacobi preconditioning
333: This works for AIJ and BAIJ matrices and uses the blocksize provided to the matrix
335: Uses dense LU factorization with partial pivoting to invert the blocks; if a zero pivot
336: is detected a PETSc error is generated.
338: Developer Notes:
339: This should support the PCSetErrorIfFailure() flag set to PETSC_TRUE to allow
340: the factorization to continue even after a zero pivot is found resulting in a Nan and hence
341: terminating KSP with a KSP_DIVERGED_NANORIF allowing
342: a nonlinear solver/ODE integrator to recover without stopping the program as currently happens.
344: Developer Note: Perhaps should provide an option that allows generation of a valid preconditioner
345: even if a block is singular as the PCJACOBI does.
347: Level: beginner
350: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PC, PCJACOBI
352: M*/
354: PETSC_EXTERN PetscErrorCode PCCreate_PBJacobi(PC pc)
355: {
356: PC_PBJacobi *jac;
360: /*
361: Creates the private data structure for this preconditioner and
362: attach it to the PC object.
363: */
364: PetscNewLog(pc,&jac);
365: pc->data = (void*)jac;
367: /*
368: Initialize the pointers to vectors to ZERO; these will be used to store
369: diagonal entries of the matrix for fast preconditioner Section 1.5 Writing Application Codes with PETSc.
370: */
371: jac->diag = 0;
373: /*
374: Set the pointers for the functions that are provided above.
375: Now when the user-level routines (such as PCApply(), PCDestroy(), etc.)
376: are called, they will automatically call these functions. Note we
377: choose not to provide a couple of these functions since they are
378: not needed.
379: */
380: pc->ops->apply = 0; /*set depending on the block size */
381: pc->ops->applytranspose = 0;
382: pc->ops->setup = PCSetUp_PBJacobi;
383: pc->ops->destroy = PCDestroy_PBJacobi;
384: pc->ops->setfromoptions = 0;
385: pc->ops->view = PCView_PBJacobi;
386: pc->ops->applyrichardson = 0;
387: pc->ops->applysymmetricleft = 0;
388: pc->ops->applysymmetricright = 0;
389: return(0);
390: }