Actual source code: ex11.c

petsc-3.13.4 2020-08-01
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  1: static const char help[] = "Solves a Q1-P0 Stokes problem from Underworld.\n\
  2: \n\
  3: You can obtain a sample matrix from http://ftp.mcs.anl.gov/pub/petsc/Datafiles/matrices/underworld32.gz\n\
  4: and run with -f underworld32.gz\n\n";

  6:  #include <petscksp.h>
  7:  #include <petscdmda.h>

  9: static PetscErrorCode replace_submats(Mat A, IS isu, IS isp)
 10: {
 12:   Mat            A11,A22,A12,A21;
 13:   Mat            nA11,nA22,nA12,nA21;
 14:   const char     *prefix;

 17:   MatCreateSubMatrix(A,isu,isu,MAT_INITIAL_MATRIX,&A11);
 18:   MatCreateSubMatrix(A,isu,isp,MAT_INITIAL_MATRIX,&A12);
 19:   MatCreateSubMatrix(A,isp,isu,MAT_INITIAL_MATRIX,&A21);
 20:   MatCreateSubMatrix(A,isp,isp,MAT_INITIAL_MATRIX,&A22);
 21:   MatDuplicate(A11,MAT_COPY_VALUES,&nA11);
 22:   MatDuplicate(A12,MAT_COPY_VALUES,&nA12);
 23:   MatDuplicate(A21,MAT_COPY_VALUES,&nA21);
 24:   MatDuplicate(A22,MAT_COPY_VALUES,&nA22);
 25:   MatGetOptionsPrefix(A11,&prefix);
 26:   MatSetOptionsPrefix(nA11,prefix);
 27:   MatGetOptionsPrefix(A22,&prefix);
 28:   MatSetOptionsPrefix(nA22,prefix);
 29:   MatNestSetSubMat(A,0,0,nA11);
 30:   MatNestSetSubMat(A,0,1,nA12);
 31:   MatNestSetSubMat(A,1,0,nA21);
 32:   MatNestSetSubMat(A,1,1,nA22);
 33:   MatDestroy(&A11);
 34:   MatDestroy(&A12);
 35:   MatDestroy(&A21);
 36:   MatDestroy(&A22);
 37:   MatDestroy(&nA11);
 38:   MatDestroy(&nA12);
 39:   MatDestroy(&nA21);
 40:   MatDestroy(&nA22);
 41:   return(0);
 42: }

 44: PetscErrorCode LSCLoadTestOperators(Mat *A11,Mat *A12,Mat *A21,Mat *A22,Vec *b1,Vec *b2)
 45: {
 46:   PetscViewer    viewer;
 48:   char           filename[PETSC_MAX_PATH_LEN];
 49:   PetscBool      flg;

 52:   MatCreate(PETSC_COMM_WORLD,A11);
 53:   MatCreate(PETSC_COMM_WORLD,A12);
 54:   MatCreate(PETSC_COMM_WORLD,A21);
 55:   MatCreate(PETSC_COMM_WORLD,A22);
 56:   MatSetOptionsPrefix(*A11,"a11_");
 57:   MatSetOptionsPrefix(*A22,"a22_");
 58:   MatSetFromOptions(*A11);
 59:   MatSetFromOptions(*A22);
 60:   VecCreate(PETSC_COMM_WORLD,b1);
 61:   VecCreate(PETSC_COMM_WORLD,b2);
 62:   /* Load matrices from a Q1-P0 discretisation of variable viscosity Stokes. The matrix blocks are packed into one file. */
 63:   PetscOptionsGetString(NULL,NULL,"-f",filename,sizeof(filename),&flg);
 64:   if (!flg) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_USER,"Must provide a matrix file with -f");
 65:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);
 66:   MatLoad(*A11,viewer);
 67:   MatLoad(*A12,viewer);
 68:   MatLoad(*A21,viewer);
 69:   MatLoad(*A22,viewer);
 70:   VecLoad(*b1,viewer);
 71:   VecLoad(*b2,viewer);
 72:   PetscViewerDestroy(&viewer);
 73:   return(0);
 74: }

 76: PetscErrorCode LoadTestMatrices(Mat *_A,Vec *_x,Vec *_b,IS *_isu,IS *_isp)
 77: {
 78:   Vec            f,h,x,b,bX[2];
 79:   Mat            A,Auu,Aup,Apu,App,bA[2][2];
 80:   IS             is_u,is_p,bis[2];
 81:   PetscInt       lnu,lnp,nu,np,i,start_u,end_u,start_p,end_p;
 82:   VecScatter     *vscat;
 83:   PetscMPIInt    rank;

 87:   /* fetch test matrices and vectors */
 88:   LSCLoadTestOperators(&Auu,&Aup,&Apu,&App,&f,&h);

 90:   /* build the mat-nest */
 91:   VecGetSize(f,&nu);
 92:   VecGetSize(h,&np);

 94:   VecGetLocalSize(f,&lnu);
 95:   VecGetLocalSize(h,&lnp);

 97:   VecGetOwnershipRange(f,&start_u,&end_u);
 98:   VecGetOwnershipRange(h,&start_p,&end_p);

100:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
101:   PetscSynchronizedPrintf(PETSC_COMM_WORLD,"[%d] lnu = %D | lnp = %D \n", rank, lnu, lnp);
102:   PetscSynchronizedPrintf(PETSC_COMM_WORLD,"[%d] s_u = %D | e_u = %D \n", rank, start_u, end_u);
103:   PetscSynchronizedPrintf(PETSC_COMM_WORLD,"[%d] s_p = %D | e_p = %D \n", rank, start_p, end_p);
104:   PetscSynchronizedPrintf(PETSC_COMM_WORLD,"[%d] is_u (offset) = %D \n", rank, start_u+start_p);
105:   PetscSynchronizedPrintf(PETSC_COMM_WORLD,"[%d] is_p (offset) = %D \n", rank, start_u+start_p+lnu);
106:   PetscSynchronizedFlush(PETSC_COMM_WORLD,PETSC_STDOUT);

108:   ISCreateStride(PETSC_COMM_WORLD,lnu,start_u+start_p,1,&is_u);
109:   ISCreateStride(PETSC_COMM_WORLD,lnp,start_u+start_p+lnu,1,&is_p);

111:   bis[0]   = is_u; bis[1]   = is_p;
112:   bA[0][0] = Auu;  bA[0][1] = Aup;
113:   bA[1][0] = Apu;  bA[1][1] = App;
114:   MatCreateNest(PETSC_COMM_WORLD,2,bis,2,bis,&bA[0][0],&A);
115:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
116:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

118:   /* Pull f,h into b */
119:   MatCreateVecs(A,&b,&x);
120:   bX[0] = f;  bX[1] = h;
121:   PetscMalloc1(2,&vscat);
122:   for (i=0; i<2; i++) {
123:     VecScatterCreate(b,bis[i],bX[i],NULL,&vscat[i]);
124:     VecScatterBegin(vscat[i],bX[i],b,INSERT_VALUES,SCATTER_REVERSE);
125:     VecScatterEnd(vscat[i],bX[i],b,INSERT_VALUES,SCATTER_REVERSE);
126:     VecScatterDestroy(&vscat[i]);
127:   }

129:   PetscFree(vscat);
130:   MatDestroy(&Auu);
131:   MatDestroy(&Aup);
132:   MatDestroy(&Apu);
133:   MatDestroy(&App);
134:   VecDestroy(&f);
135:   VecDestroy(&h);

137:   *_isu = is_u;
138:   *_isp = is_p;
139:   *_A   = A;
140:   *_x   = x;
141:   *_b   = b;
142:   return(0);
143: }


146: PetscErrorCode port_lsd_bfbt(void)
147: {
148:   Mat            A,P;
149:   Vec            x,b;
150:   KSP            ksp_A;
151:   PC             pc_A;
152:   IS             isu,isp;
153:   PetscBool      test_fs = PETSC_FALSE;

157:   LoadTestMatrices(&A,&x,&b,&isu,&isp);
158:   PetscOptionsGetBool(NULL,NULL,"-test_fs",&test_fs,NULL);
159:   if (!test_fs) {
160:     PetscObjectReference((PetscObject)A);
161:     P = A;
162:   } else {
163:     MatDuplicate(A,MAT_COPY_VALUES,&P);
164:   }
165:   KSPCreate(PETSC_COMM_WORLD,&ksp_A);
166:   KSPSetOptionsPrefix(ksp_A,"fc_");
167:   KSPSetOperators(ksp_A,A,P);

169:   KSPGetPC(ksp_A,&pc_A);
170:   PCSetType(pc_A,PCFIELDSPLIT);
171:   PCFieldSplitSetBlockSize(pc_A,2);
172:   PCFieldSplitSetIS(pc_A,"velocity",isu);
173:   PCFieldSplitSetIS(pc_A,"pressure",isp);

175:   KSPSetFromOptions(ksp_A);
176:   KSPSolve(ksp_A,b,x);

178:   /* Pull u,p out of x */
179:   {
180:     PetscInt    loc;
181:     PetscReal   max,norm;
182:     PetscScalar sum;
183:     Vec         uvec,pvec;
184:     VecScatter  uscat,pscat;
185:     Mat         A11,A22;

187:     /* grab matrices and create the compatable u,p vectors */
188:     MatCreateSubMatrix(A,isu,isu,MAT_INITIAL_MATRIX,&A11);
189:     MatCreateSubMatrix(A,isp,isp,MAT_INITIAL_MATRIX,&A22);

191:     MatCreateVecs(A11,&uvec,NULL);
192:     MatCreateVecs(A22,&pvec,NULL);

194:     /* perform the scatter from x -> (u,p) */
195:     VecScatterCreate(x,isu,uvec,NULL,&uscat);
196:     VecScatterBegin(uscat,x,uvec,INSERT_VALUES,SCATTER_FORWARD);
197:     VecScatterEnd(uscat,x,uvec,INSERT_VALUES,SCATTER_FORWARD);

199:     VecScatterCreate(x,isp,pvec,NULL,&pscat);
200:     VecScatterBegin(pscat,x,pvec,INSERT_VALUES,SCATTER_FORWARD);
201:     VecScatterEnd(pscat,x,pvec,INSERT_VALUES,SCATTER_FORWARD);

203:     PetscPrintf(PETSC_COMM_WORLD,"-- vector vector values --\n");
204:     VecMin(uvec,&loc,&max);
205:     PetscPrintf(PETSC_COMM_WORLD,"  Min(u)  = %1.6f [loc=%D]\n",(double)max,loc);
206:     VecMax(uvec,&loc,&max);
207:     PetscPrintf(PETSC_COMM_WORLD,"  Max(u)  = %1.6f [loc=%D]\n",(double)max,loc);
208:     VecNorm(uvec,NORM_2,&norm);
209:     PetscPrintf(PETSC_COMM_WORLD,"  Norm(u) = %1.6f \n",(double)norm);
210:     VecSum(uvec,&sum);
211:     PetscPrintf(PETSC_COMM_WORLD,"  Sum(u)  = %1.6f \n",(double)PetscRealPart(sum));

213:     PetscPrintf(PETSC_COMM_WORLD,"-- pressure vector values --\n");
214:     VecMin(pvec,&loc,&max);
215:     PetscPrintf(PETSC_COMM_WORLD,"  Min(p)  = %1.6f [loc=%D]\n",(double)max,loc);
216:     VecMax(pvec,&loc,&max);
217:     PetscPrintf(PETSC_COMM_WORLD,"  Max(p)  = %1.6f [loc=%D]\n",(double)max,loc);
218:     VecNorm(pvec,NORM_2,&norm);
219:     PetscPrintf(PETSC_COMM_WORLD,"  Norm(p) = %1.6f \n",(double)norm);
220:     VecSum(pvec,&sum);
221:     PetscPrintf(PETSC_COMM_WORLD,"  Sum(p)  = %1.6f \n",(double)PetscRealPart(sum));

223:     PetscPrintf(PETSC_COMM_WORLD,"-- Full vector values --\n");
224:     VecMin(x,&loc,&max);
225:     PetscPrintf(PETSC_COMM_WORLD,"  Min(u,p)  = %1.6f [loc=%D]\n",(double)max,loc);
226:     VecMax(x,&loc,&max);
227:     PetscPrintf(PETSC_COMM_WORLD,"  Max(u,p)  = %1.6f [loc=%D]\n",(double)max,loc);
228:     VecNorm(x,NORM_2,&norm);
229:     PetscPrintf(PETSC_COMM_WORLD,"  Norm(u,p) = %1.6f \n",(double)norm);
230:     VecSum(x,&sum);
231:     PetscPrintf(PETSC_COMM_WORLD,"  Sum(u,p)  = %1.6f \n",(double)PetscRealPart(sum));

233:     VecScatterDestroy(&uscat);
234:     VecScatterDestroy(&pscat);
235:     VecDestroy(&uvec);
236:     VecDestroy(&pvec);
237:     MatDestroy(&A11);
238:     MatDestroy(&A22);
239:   }

241:   /* test second solve by changing the mat associated to the MATNEST blocks */
242:   {
243:     replace_submats(A,isu,isp);
244:     replace_submats(P,isu,isp);
245:     KSPSolve(ksp_A,b,x);
246:   }

248:   KSPDestroy(&ksp_A);
249:   MatDestroy(&P);
250:   MatDestroy(&A);
251:   VecDestroy(&x);
252:   VecDestroy(&b);
253:   ISDestroy(&isu);
254:   ISDestroy(&isp);
255:   return(0);
256: }


259: int main(int argc,char **argv)
260: {

263:   PetscInitialize(&argc,&argv,0,help);if (ierr) return ierr;
264:   port_lsd_bfbt();
265:   PetscFinalize();
266:   return ierr;
267: }

269: /*TEST

271:     test:
272:       args: -f ${DATAFILESPATH}/matrices/underworld32.gz -fc_ksp_view -fc_ksp_monitor_short -fc_ksp_type fgmres -fc_ksp_max_it 4000 -fc_ksp_diagonal_scale -fc_pc_type fieldsplit  -fc_pc_fieldsplit_type SCHUR -fc_pc_fieldsplit_schur_fact_type UPPER -fc_fieldsplit_velocity_ksp_type cg -fc_fieldsplit_velocity_pc_type cholesky -fc_fieldsplit_velocity_pc_factor_mat_ordering_type nd -fc_fieldsplit_pressure_ksp_max_it 100 -fc_fieldsplit_pressure_ksp_constant_null_space -fc_fieldsplit_pressure_ksp_monitor_short -fc_fieldsplit_pressure_pc_type lsc -fc_fieldsplit_pressure_lsc_ksp_type cg -fc_fieldsplit_pressure_lsc_ksp_max_it 100 -fc_fieldsplit_pressure_lsc_ksp_constant_null_space -fc_fieldsplit_pressure_lsc_ksp_converged_reason -fc_fieldsplit_pressure_lsc_pc_type icc -test_fs {{0 1}separate output} -fc_pc_fieldsplit_off_diag_use_amat {{0 1}separate output} -fc_pc_fieldsplit_diag_use_amat {{0 1}separate output}
273:       requires: datafilespath double !complex !define(PETSC_USE_64BIT_INDICES)

275:     test:
276:       suffix: 2
277:       nsize: 4
278:       args: -f ${DATAFILESPATH}/matrices/underworld32.gz -fc_ksp_view -fc_ksp_monitor_short -fc_ksp_type fgmres -fc_ksp_max_it 4000 -fc_ksp_diagonal_scale -fc_pc_type fieldsplit -fc_pc_fieldsplit_type SCHUR -fc_pc_fieldsplit_schur_fact_type UPPER -fc_fieldsplit_velocity_ksp_type cg -fc_fieldsplit_velocity_ksp_rtol 1.0e-6 -fc_fieldsplit_velocity_pc_type bjacobi -fc_fieldsplit_velocity_sub_pc_type cholesky -fc_fieldsplit_velocity_sub_pc_factor_mat_ordering_type nd -fc_fieldsplit_pressure_ksp_type fgmres -fc_fieldsplit_pressure_ksp_constant_null_space -fc_fieldsplit_pressure_ksp_monitor_short  -fc_fieldsplit_pressure_pc_type lsc -fc_fieldsplit_pressure_lsc_ksp_type cg -fc_fieldsplit_pressure_lsc_ksp_rtol 1.0e-2 -fc_fieldsplit_pressure_lsc_ksp_constant_null_space -fc_fieldsplit_pressure_lsc_ksp_converged_reason -fc_fieldsplit_pressure_lsc_pc_type bjacobi -fc_fieldsplit_pressure_lsc_sub_pc_type icc -test_fs {{0 1}separate output} -fc_pc_fieldsplit_off_diag_use_amat {{0 1}separate output} -fc_pc_fieldsplit_diag_use_amat {{0 1}separate output}
279:       requires: datafilespath double  !complex !define(PETSC_USE_64BIT_INDICES)

281: TEST*/