Actual source code: ex178.c


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

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

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

 17:   PetscFunctionBeginUser;
 18:   PetscCall(PetscInitialize(&argc, &argv, (char *)0, help));
 19:   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_DENSE));

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

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

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

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

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

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

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

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

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

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

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

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

 99:   PetscCall(PetscFinalize());
100:   return 0;
101: }

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

110:   PetscFunctionBeginUser;
111:   PetscCall(MatGetOwnershipRange(A, &rstart, &rend));
112:   for (i = rstart; i < rend; i++) {
113:     founddiag = PETSC_FALSE;
114:     PetscCall(MatGetRow(A, i, &ncols, &cols, &vals));
115:     for (j = 0; j < ncols; j++) {
116:       if (cols[j] == i) {
117:         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]));
118:         founddiag = PETSC_TRUE;
119:       } else {
120:         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]);
121:       }
122:     }
123:     PetscCall(MatRestoreRow(A, i, &ncols, &cols, &vals));
124:     PetscCheck(founddiag, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Row %" PetscInt_FMT " does not have diagonal entry", i);
125:   }
126:   PetscFunctionReturn(PETSC_SUCCESS);
127: }

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

137:   PetscFunctionBeginUser;
138:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
139:   PetscCall(MatCreateAIJ(PETSC_COMM_WORLD, parts[rank], parts[rank], PETSC_DETERMINE, PETSC_DETERMINE, 0, NULL, 0, NULL, A));
140:   PetscCall(MatSetOption(*A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE));
141:   if (rank == 0) {
142:     for (i = 0; i < nblocks; i++) {
143:       PetscCall(MatSetValue(*A, cnt, cnt + blocksizes[i] - 1, 1.0, INSERT_VALUES));
144:       PetscCall(MatSetValue(*A, cnt + blocksizes[i] - 1, cnt, 1.0, INSERT_VALUES));
145:       cnt += blocksizes[i];
146:     }
147:   }
148:   PetscCall(MatAssemblyBegin(*A, MAT_FINAL_ASSEMBLY));
149:   PetscCall(MatAssemblyEnd(*A, MAT_FINAL_ASSEMBLY));
150:   PetscCall(MatShift(*A, 10));
151:   PetscFunctionReturn(PETSC_SUCCESS);
152: }

154: /*TEST

156:    test:

158:    test:
159:      suffix: 2
160:      nsize: 2

162:    test:
163:      suffix: 5
164:      nsize: 5

166: TEST*/