Actual source code: ex57.c


  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";

  9: #include <petscmat.h>
 10: #include <petscvec.h>

 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;

 25:   PetscInitialize(&argc, &args, (char *)0, help);
 26:   PetscOptionsGetString(NULL, NULL, "-fin", fin, sizeof(fin), &flg);
 28:   PetscViewerBinaryOpen(PETSC_COMM_SELF, fin, FILE_MODE_READ, &fdin);

 30:   PetscOptionsGetString(NULL, NULL, "-fout", fout, sizeof(fout), &flg);
 31:   if (!flg) PetscPrintf(PETSC_COMM_WORLD, "Writing submatrix to file : %s\n", fout);
 32:   PetscViewerBinaryOpen(PETSC_COMM_SELF, fout, FILE_MODE_WRITE, &fdout);

 34:   MatCreate(PETSC_COMM_SELF, &A);
 35:   MatSetType(A, mtype);
 36:   MatLoad(A, fdin);
 37:   PetscViewerDestroy(&fdin);

 39:   MatGetSize(A, &m, &m);
 40:   m /= 2;
 41:   PetscOptionsGetInt(NULL, NULL, "-start", &start, NULL);
 42:   PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL);

 44:   ISCreateStride(PETSC_COMM_SELF, m, start, 1, &isrow);
 45:   ISCreateStride(PETSC_COMM_SELF, m, start, 1, &iscol);
 46:   MatCreateSubMatrices(A, 1, &isrow, &iscol, MAT_INITIAL_MATRIX, &B);
 47:   MatView(B[0], fdout);

 49:   VecCreate(PETSC_COMM_SELF, &b);
 50:   VecSetSizes(b, PETSC_DECIDE, m);
 51:   VecSetFromOptions(b);
 52:   MatView(B[0], fdout);
 53:   PetscViewerDestroy(&fdout);

 55:   MatDestroy(&A);
 56:   MatDestroy(&B[0]);
 57:   VecDestroy(&b);
 58:   PetscFree(B);
 59:   ISDestroy(&iscol);
 60:   ISDestroy(&isrow);
 61:   PetscFinalize();
 62:   return 0;
 63: }

 65: /*TEST

 67:     test:
 68:       args: -fin ${DATAFILESPATH}/matrices/small -fout joe -start 2 -m 4
 69:       requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)

 71: TEST*/