1 static char help[] = "Reads in a binary file, extracts a submatrix from it, and writes to another binary file.\n\ 2 Options:\n\ 3 -fin <mat> : input matrix file\n\ 4 -fout <mat> : output marrix file\n\ 5 -start <row> : the row from where the submat should be extracted\n\ 6 -m <sx> : the size of the submatrix\n"; 7 8 #include <petscmat.h> 9 #include <petscvec.h> 10 11 int main(int argc, char **args) 12 { 13 char fin[PETSC_MAX_PATH_LEN], fout[PETSC_MAX_PATH_LEN] = "default.mat"; 14 PetscViewer fdin, fdout; 15 Vec b; 16 MatType mtype = MATSEQBAIJ; 17 Mat A, *B; 18 PetscInt start = 0; 19 PetscInt m; 20 IS isrow, iscol; 21 PetscBool flg; 22 23 PetscFunctionBeginUser; 24 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 25 PetscCall(PetscOptionsGetString(NULL, NULL, "-fin", fin, sizeof(fin), &flg)); 26 PetscCheck(flg, PETSC_COMM_WORLD, PETSC_ERR_USER, "Must indicate binary file with the -fin option"); 27 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fin, FILE_MODE_READ, &fdin)); 28 29 PetscCall(PetscOptionsGetString(NULL, NULL, "-fout", fout, sizeof(fout), &flg)); 30 if (!flg) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Writing submatrix to file : %s\n", fout)); 31 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fout, FILE_MODE_WRITE, &fdout)); 32 33 PetscCall(MatCreate(PETSC_COMM_SELF, &A)); 34 PetscCall(MatSetType(A, mtype)); 35 PetscCall(MatLoad(A, fdin)); 36 PetscCall(PetscViewerDestroy(&fdin)); 37 38 PetscCall(MatGetSize(A, &m, &m)); 39 m /= 2; 40 PetscCall(PetscOptionsGetInt(NULL, NULL, "-start", &start, NULL)); 41 PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL)); 42 43 PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &isrow)); 44 PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &iscol)); 45 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &iscol, MAT_INITIAL_MATRIX, &B)); 46 PetscCall(MatView(B[0], fdout)); 47 48 PetscCall(VecCreate(PETSC_COMM_SELF, &b)); 49 PetscCall(VecSetSizes(b, PETSC_DECIDE, m)); 50 PetscCall(VecSetFromOptions(b)); 51 PetscCall(MatView(B[0], fdout)); 52 PetscCall(PetscViewerDestroy(&fdout)); 53 54 PetscCall(MatDestroy(&A)); 55 PetscCall(MatDestroy(&B[0])); 56 PetscCall(VecDestroy(&b)); 57 PetscCall(PetscFree(B)); 58 PetscCall(ISDestroy(&iscol)); 59 PetscCall(ISDestroy(&isrow)); 60 PetscCall(PetscFinalize()); 61 return 0; 62 } 63 64 /*TEST 65 66 test: 67 args: -fin ${DATAFILESPATH}/matrices/small -fout joe -start 2 -m 4 68 requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES) 69 70 TEST*/ 71