Actual source code: ex4.c


  2: static char help[] = "Solves a linear system in parallel with KSP and HMG.\n\
  3: Input parameters include:\n\
  4:   -view_exact_sol    : write exact solution vector to stdout\n\
  5:   -m  <mesh_x>       : number of mesh points in x-direction\n\
  6:   -n  <mesh_y>       : number of mesh points in y-direction\n\
  7:   -bs                : number of variables on each mesh vertex \n\n";

  9: /*
 10:   Simple example is used to test PCHMG
 11: */
 12: #include <petscksp.h>

 14: int main(int argc,char **args)
 15: {
 16:   Vec            x,b,u;    /* approx solution, RHS, exact solution */
 17:   Mat            A;        /* linear system matrix */
 18:   KSP            ksp;      /* linear solver context */
 19:   PetscReal      norm;     /* norm of solution error */
 20:   PetscInt       i,j,Ii,J,Istart,Iend,m = 8,n = 7,its,bs=1,II,JJ,jj;
 22:   PetscBool      flg,test=PETSC_FALSE,reuse=PETSC_FALSE,viewexpl=PETSC_FALSE;
 23:   PetscScalar    v;
 24:   PC             pc;

 26:   PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
 27:   PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
 28:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 29:   PetscOptionsGetInt(NULL,NULL,"-bs",&bs,NULL);
 30:   PetscOptionsGetBool(NULL,NULL,"-test_hmg_interface",&test,NULL);
 31:   PetscOptionsGetBool(NULL,NULL,"-test_reuse_interpolation",&reuse,NULL);
 32:   PetscOptionsGetBool(NULL,NULL,"-view_explicit_mat",&viewexpl,NULL);

 34:   MatCreate(PETSC_COMM_WORLD,&A);
 35:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m*n*bs,m*n*bs);
 36:   MatSetBlockSize(A,bs);
 37:   MatSetFromOptions(A);
 38:   MatMPIAIJSetPreallocation(A,5,NULL,5,NULL);
 39:   MatSeqAIJSetPreallocation(A,5,NULL);
 40: #if defined(PETSC_HAVE_HYPRE)
 41:   MatHYPRESetPreallocation(A,5,NULL,5,NULL);
 42: #endif

 44:   MatGetOwnershipRange(A,&Istart,&Iend);

 46:   for (Ii=Istart/bs; Ii<Iend/bs; Ii++) {
 47:     v = -1.0; i = Ii/n; j = Ii - i*n;
 48:     if (i>0) {
 49:       J = Ii - n;
 50:       for (jj=0; jj<bs; jj++) {
 51:         II = Ii*bs + jj;
 52:         JJ = J*bs + jj;
 53:         MatSetValues(A,1,&II,1,&JJ,&v,ADD_VALUES);
 54:       }
 55:     }
 56:     if (i<m-1) {
 57:       J = Ii + n;
 58:       for (jj=0; jj<bs; jj++) {
 59:         II = Ii*bs + jj;
 60:         JJ = J*bs + jj;
 61:         MatSetValues(A,1,&II,1,&JJ,&v,ADD_VALUES);
 62:       }
 63:     }
 64:     if (j>0) {
 65:       J = Ii - 1;
 66:       for (jj=0; jj<bs; jj++) {
 67:         II = Ii*bs + jj;
 68:         JJ = J*bs + jj;
 69:         MatSetValues(A,1,&II,1,&JJ,&v,ADD_VALUES);
 70:       }
 71:     }
 72:     if (j<n-1) {
 73:       J = Ii + 1;
 74:       for (jj=0; jj<bs; jj++) {
 75:         II = Ii*bs + jj;
 76:         JJ = J*bs + jj;
 77:         MatSetValues(A,1,&II,1,&JJ,&v,ADD_VALUES);
 78:       }
 79:     }
 80:     v = 4.0;
 81:     for (jj=0; jj<bs; jj++) {
 82:       II = Ii*bs + jj;
 83:       MatSetValues(A,1,&II,1,&II,&v,ADD_VALUES);
 84:     }
 85:   }

 87:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 88:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
 89:   if (viewexpl) {
 90:     Mat E;
 91:     MatComputeOperator(A,MATAIJ,&E);
 92:     MatView(E,NULL);
 93:     MatDestroy(&E);
 94:   }

 96:   MatCreateVecs(A,&u,NULL);
 97:   VecSetFromOptions(u);
 98:   VecDuplicate(u,&b);
 99:   VecDuplicate(b,&x);

101:   VecSet(u,1.0);
102:   MatMult(A,u,b);

104:   flg  = PETSC_FALSE;
105:   PetscOptionsGetBool(NULL,NULL,"-view_exact_sol",&flg,NULL);
106:   if (flg) {VecView(u,PETSC_VIEWER_STDOUT_WORLD);}

108:   KSPCreate(PETSC_COMM_WORLD,&ksp);
109:   KSPSetOperators(ksp,A,A);
110:   KSPSetTolerances(ksp,1.e-2/((m+1)*(n+1)),1.e-50,PETSC_DEFAULT,PETSC_DEFAULT);

112:   if (test) {
113:     KSPGetPC(ksp,&pc);
114:     PCSetType(pc,PCHMG);
115:     PCHMGSetInnerPCType(pc,PCGAMG);
116:     PCHMGSetReuseInterpolation(pc,PETSC_TRUE);
117:     PCHMGSetUseSubspaceCoarsening(pc,PETSC_TRUE);
118:     PCHMGUseMatMAIJ(pc,PETSC_FALSE);
119:     PCHMGSetCoarseningComponent(pc,0);
120:   }

122:   KSPSetFromOptions(ksp);
123:   KSPSolve(ksp,b,x);

125:   if (reuse) {
126:     MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
127:     MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
128:     KSPSolve(ksp,b,x);
129:     MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
130:     MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
131:     KSPSolve(ksp,b,x);
132:     /* Make sparsity pattern different and reuse interpolation */
133:     MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);
134:     MatSetOption(A,MAT_IGNORE_ZERO_ENTRIES,PETSC_FALSE);
135:     MatGetSize(A,&m,NULL);
136:     n = 0;
137:     v = 0;
138:     m--;
139:     /* Connect the last element to the first element */
140:     MatSetValue(A,m,n,v,ADD_VALUES);
141:     MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
142:     MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
143:     KSPSolve(ksp,b,x);
144:   }

146:   VecAXPY(x,-1.0,u);
147:   VecNorm(x,NORM_2,&norm);
148:   KSPGetIterationNumber(ksp,&its);

150:   PetscPrintf(PETSC_COMM_WORLD,"Norm of error %g iterations %D\n",(double)norm,its);

152:   KSPDestroy(&ksp);
153:   VecDestroy(&u);
154:   VecDestroy(&x);
155:   VecDestroy(&b);
156:   MatDestroy(&A);

158:   PetscFinalize();
159:   return ierr;
160: }

162: /*TEST

164:    build:
165:       requires: !complex !single

167:    test:
168:       suffix: hypre
169:       nsize: 2
170:       requires: hypre !defined(PETSC_HAVE_HYPRE_DEVICE)
171:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type hypre

173:    test:
174:       suffix: hypre_bs4
175:       nsize: 2
176:       requires: hypre !defined(PETSC_HAVE_HYPRE_DEVICE)
177:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type hypre -bs 4 -pc_hmg_use_subspace_coarsening 1

179:    test:
180:       suffix: hypre_asm
181:       nsize: 2
182:       requires: hypre !defined(PETSC_HAVE_HYPRE_DEVICE)
183:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type hypre -bs 4 -pc_hmg_use_subspace_coarsening 1 -mg_levels_3_pc_type asm

185:    test:
186:       suffix: hypre_fieldsplit
187:       nsize: 2
188:       requires: hypre !defined(PETSC_HAVE_HYPRE_DEVICE)
189:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type hypre -bs 4 -mg_levels_4_pc_type fieldsplit

191:    test:
192:       suffix: gamg
193:       nsize: 2
194:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type gamg

196:    test:
197:       suffix: gamg_bs4
198:       nsize: 2
199:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type gamg -bs 4 -pc_hmg_use_subspace_coarsening 1

201:    test:
202:       suffix: gamg_asm
203:       nsize: 2
204:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type gamg -bs 4 -pc_hmg_use_subspace_coarsening 1 -mg_levels_1_pc_type asm

206:    test:
207:       suffix: gamg_fieldsplit
208:       nsize: 2
209:       args: -ksp_monitor -pc_type hmg -ksp_rtol 1e-6 -hmg_inner_pc_type gamg -bs 4 -mg_levels_1_pc_type fieldsplit

211:    test:
212:       suffix: interface
213:       nsize: 2
214:       args: -ksp_monitor -ksp_rtol 1e-6 -test_hmg_interface 1 -bs 4

216:    test:
217:       suffix: reuse
218:       nsize: 2
219:       args: -ksp_monitor -ksp_rtol 1e-6   -pc_type hmg -pc_hmg_reuse_interpolation 1 -test_reuse_interpolation 1 -hmg_inner_pc_type gamg

221:    test:
222:       suffix: component
223:       nsize: 2
224:       args: -ksp_monitor -ksp_rtol 1e-6 -pc_type hmg -pc_hmg_coarsening_component 2  -pc_hmg_use_subspace_coarsening 1 -bs 4 -hmg_inner_pc_type gamg

226:    testset:
227:       output_file: output/ex4_expl.out
228:       nsize: {{1 2}}
229:       filter: grep -v "MPI processes" | grep -v " type:" | grep -v "Mat Object"
230:       args: -ksp_converged_reason -view_explicit_mat -pc_type none -ksp_type {{cg gmres}}
231:       test:
232:         suffix: expl_aij
233:         args: -mat_type aij
234:       test:
235:         suffix: expl_hypre
236:         requires: hypre
237:         args: -mat_type hypre

239:    test:
240:       suffix: hypre_device
241:       nsize: {{1 2}}
242:       requires: hypre defined(PETSC_HAVE_HYPRE_DEVICE)
243:       args: -mat_type hypre -ksp_converged_reason -pc_type hypre -m 13 -n 17

245:    test:
246:       suffix: hypre_device_cusparse
247:       output_file: output/ex4_hypre_device.out
248:       nsize: {{1 2}}
249:       requires: hypre cuda defined(PETSC_HAVE_HYPRE_DEVICE)
250:       args: -mat_type {{aij aijcusparse}} -vec_type cuda -ksp_converged_reason -pc_type hypre -m 13 -n 17

252: TEST*/