Actual source code: ex178.c

  1: static char help[] = "Tests MatInvertVariableBlockEnvelope()\n\n";

  3: #include <petscmat.h>
  4: extern PetscErrorCode MatIsDiagonal(Mat);
  5: extern PetscErrorCode BuildMatrix(const PetscInt *, PetscInt, const PetscInt *, Mat *);

  7: int main(int argc, char **argv)
  8: {
  9:   Mat         A, C, D, F;
 10:   PetscInt    i, j, rows[2], *parts, cnt, N = 21, nblocks, *blocksizes;
 11:   PetscScalar values[2][2];
 12:   PetscReal   rand;
 13:   PetscRandom rctx;
 14:   PetscMPIInt size;

 16:   PetscFunctionBeginUser;
 17:   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
 18:   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_DENSE));

 20:   PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
 21:   PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, 6, 18));
 22:   PetscCall(MatSetFromOptions(C));
 23:   PetscCall(MatSetUp(C));
 24:   values[0][0] = 2;
 25:   values[0][1] = 1;
 26:   values[1][0] = 1;
 27:   values[1][1] = 2;
 28:   for (i = 0; i < 3; i++) {
 29:     rows[0] = 2 * i;
 30:     rows[1] = 2 * i + 1;
 31:     PetscCall(MatSetValues(C, 2, rows, 2, rows, (PetscScalar *)values, INSERT_VALUES));
 32:   }
 33:   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
 34:   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
 35:   PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));

 37:   PetscCall(MatMatTransposeMult(C, C, MAT_INITIAL_MATRIX, PETSC_DETERMINE, &A));
 38:   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));

 40:   PetscCall(MatInvertVariableBlockEnvelope(A, MAT_INITIAL_MATRIX, &D));
 41:   PetscCall(MatView(D, PETSC_VIEWER_STDOUT_WORLD));

 43:   PetscCall(MatMatMult(A, D, MAT_INITIAL_MATRIX, 1.0, &F));
 44:   PetscCall(MatView(F, PETSC_VIEWER_STDOUT_WORLD));
 45:   PetscCall(MatIsDiagonal(F));

 47:   PetscCall(MatDestroy(&A));
 48:   PetscCall(MatDestroy(&D));
 49:   PetscCall(MatDestroy(&C));
 50:   PetscCall(MatDestroy(&F));

 52:   PetscCall(PetscRandomCreate(PETSC_COMM_SELF, &rctx));
 53:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
 54:   PetscCall(PetscMalloc1(size, &parts));

 56:   for (j = 0; j < 128; j++) {
 57:     cnt = 0;
 58:     for (i = 0; i < size - 1; i++) {
 59:       PetscCall(PetscRandomGetValueReal(rctx, &rand));
 60:       parts[i] = (PetscInt)N * rand;
 61:       parts[i] = PetscMin(parts[i], N - cnt);
 62:       cnt += parts[i];
 63:     }
 64:     parts[size - 1] = N - cnt;

 66:     PetscCall(PetscRandomGetValueReal(rctx, &rand));
 67:     nblocks = rand * 10;
 68:     nblocks = PetscMax(nblocks, 2);
 69:     cnt     = 0;
 70:     PetscCall(PetscMalloc1(nblocks, &blocksizes));
 71:     for (i = 0; i < nblocks - 1; i++) {
 72:       PetscCall(PetscRandomGetValueReal(rctx, &rand));
 73:       blocksizes[i] = PetscMax(1, (PetscInt)N * rand);
 74:       blocksizes[i] = PetscMin(blocksizes[i], N - cnt);
 75:       cnt += blocksizes[i];
 76:       if (cnt == N) {
 77:         nblocks = i + 1;
 78:         break;
 79:       }
 80:     }
 81:     if (cnt < N) blocksizes[nblocks - 1] = N - cnt;

 83:     PetscCall(BuildMatrix(parts, nblocks, blocksizes, &A));
 84:     PetscCall(PetscFree(blocksizes));

 86:     PetscCall(MatInvertVariableBlockEnvelope(A, MAT_INITIAL_MATRIX, &D));

 88:     PetscCall(MatMatMult(A, D, MAT_INITIAL_MATRIX, 1.0, &F));
 89:     PetscCall(MatIsDiagonal(F));

 91:     PetscCall(MatDestroy(&A));
 92:     PetscCall(MatDestroy(&D));
 93:     PetscCall(MatDestroy(&F));
 94:   }
 95:   PetscCall(PetscFree(parts));
 96:   PetscCall(PetscRandomDestroy(&rctx));

 98:   PetscCall(PetscFinalize());
 99:   return 0;
100: }

102: PetscErrorCode MatIsDiagonal(Mat A)
103: {
104:   PetscInt           ncols, i, j, rstart, rend;
105:   const PetscInt    *cols;
106:   const PetscScalar *vals;
107:   PetscBool          founddiag;

109:   PetscFunctionBeginUser;
110:   PetscCall(MatGetOwnershipRange(A, &rstart, &rend));
111:   for (i = rstart; i < rend; i++) {
112:     founddiag = PETSC_FALSE;
113:     PetscCall(MatGetRow(A, i, &ncols, &cols, &vals));
114:     for (j = 0; j < ncols; j++) {
115:       if (cols[j] == i) {
116:         PetscCheck(PetscAbsScalar(vals[j] - 1) < PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Row %" PetscInt_FMT " does not have 1 on the diagonal, it has %g", i, (double)PetscAbsScalar(vals[j]));
117:         founddiag = PETSC_TRUE;
118:       } else {
119:         PetscCheck(PetscAbsScalar(vals[j]) < PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Row %" PetscInt_FMT " has off-diagonal value %g at %" PetscInt_FMT, i, (double)PetscAbsScalar(vals[j]), cols[j]);
120:       }
121:     }
122:     PetscCall(MatRestoreRow(A, i, &ncols, &cols, &vals));
123:     PetscCheck(founddiag, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Row %" PetscInt_FMT " does not have diagonal entry", i);
124:   }
125:   PetscFunctionReturn(PETSC_SUCCESS);
126: }

128: /*
129:     All processes receive all the block information
130: */
131: PetscErrorCode BuildMatrix(const PetscInt *parts, PetscInt nblocks, const PetscInt *blocksizes, Mat *A)
132: {
133:   PetscInt    i, cnt = 0;
134:   PetscMPIInt rank;

136:   PetscFunctionBeginUser;
137:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
138:   PetscCall(MatCreateAIJ(PETSC_COMM_WORLD, parts[rank], parts[rank], PETSC_DETERMINE, PETSC_DETERMINE, 0, NULL, 0, NULL, A));
139:   PetscCall(MatSetOption(*A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE));
140:   if (rank == 0) {
141:     for (i = 0; i < nblocks; i++) {
142:       PetscCall(MatSetValue(*A, cnt, cnt + blocksizes[i] - 1, 1.0, INSERT_VALUES));
143:       PetscCall(MatSetValue(*A, cnt + blocksizes[i] - 1, cnt, 1.0, INSERT_VALUES));
144:       cnt += blocksizes[i];
145:     }
146:   }
147:   PetscCall(MatAssemblyBegin(*A, MAT_FINAL_ASSEMBLY));
148:   PetscCall(MatAssemblyEnd(*A, MAT_FINAL_ASSEMBLY));
149:   PetscCall(MatShift(*A, 10));
150:   PetscFunctionReturn(PETSC_SUCCESS);
151: }

153: /*TEST

155:    test:

157:    test:
158:      suffix: 2
159:      nsize: 2

161:    test:
162:      suffix: 5
163:      nsize: 5

165: TEST*/