1 2 static char help[] = "Reads in a binary file, extracts a submatrix from it, and writes to another binary file.\n\ 3 Options:\n\ 4 -fin <mat> : input matrix file\n\ 5 -fout <mat> : output marrix file\n\ 6 -start <row> : the row from where the submat should be extracted\n\ 7 -m <sx> : the size of the submatrix\n"; 8 9 #include <petscmat.h> 10 #include <petscvec.h> 11 12 int main(int argc, char **args) 13 { 14 char fin[PETSC_MAX_PATH_LEN], fout[PETSC_MAX_PATH_LEN] = "default.mat"; 15 PetscViewer fdin, fdout; 16 Vec b; 17 MatType mtype = MATSEQBAIJ; 18 Mat A, *B; 19 PetscInt start = 0; 20 PetscInt m; 21 IS isrow, iscol; 22 PetscBool flg; 23 24 PetscFunctionBeginUser; 25 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 26 PetscCall(PetscOptionsGetString(NULL, NULL, "-fin", fin, sizeof(fin), &flg)); 27 PetscCheck(flg, PETSC_COMM_WORLD, PETSC_ERR_USER, "Must indicate binary file with the -fin option"); 28 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fin, FILE_MODE_READ, &fdin)); 29 30 PetscCall(PetscOptionsGetString(NULL, NULL, "-fout", fout, sizeof(fout), &flg)); 31 if (!flg) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Writing submatrix to file : %s\n", fout)); 32 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fout, FILE_MODE_WRITE, &fdout)); 33 34 PetscCall(MatCreate(PETSC_COMM_SELF, &A)); 35 PetscCall(MatSetType(A, mtype)); 36 PetscCall(MatLoad(A, fdin)); 37 PetscCall(PetscViewerDestroy(&fdin)); 38 39 PetscCall(MatGetSize(A, &m, &m)); 40 m /= 2; 41 PetscCall(PetscOptionsGetInt(NULL, NULL, "-start", &start, NULL)); 42 PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL)); 43 44 PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &isrow)); 45 PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &iscol)); 46 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &iscol, MAT_INITIAL_MATRIX, &B)); 47 PetscCall(MatView(B[0], fdout)); 48 49 PetscCall(VecCreate(PETSC_COMM_SELF, &b)); 50 PetscCall(VecSetSizes(b, PETSC_DECIDE, m)); 51 PetscCall(VecSetFromOptions(b)); 52 PetscCall(MatView(B[0], fdout)); 53 PetscCall(PetscViewerDestroy(&fdout)); 54 55 PetscCall(MatDestroy(&A)); 56 PetscCall(MatDestroy(&B[0])); 57 PetscCall(VecDestroy(&b)); 58 PetscCall(PetscFree(B)); 59 PetscCall(ISDestroy(&iscol)); 60 PetscCall(ISDestroy(&isrow)); 61 PetscCall(PetscFinalize()); 62 return 0; 63 } 64 65 /*TEST 66 67 test: 68 args: -fin ${DATAFILESPATH}/matrices/small -fout joe -start 2 -m 4 69 requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES) 70 71 TEST*/ 72