Actual source code: ex57.c

  1: /*$Id: ex57.c,v 1.23 2001/04/10 19:35:44 bsmith Exp $*/

  3: static char help[] = "Reads in a binary file, extracts a submatrix from it, and writes to another binary file.\n\
  4: Options:\n\
  5:   -fin  <mat>  : input matrix file\n\
  6:   -fout <mat>  : output marrix file\n\
  7:   -start <row> : the row from where the submat should be extracted\n\
  8:   -size  <sx>  : the size of the submatrix\n";

 10:  #include petscmat.h
 11:  #include petscvec.h

 15: int main(int argc,char **args)
 16: {
 17:   char        fin[128],fout[128] ="default.mat";
 18:   PetscViewer fdin,fdout;
 19:   Vec         b;
 20:   MatType     mtype = MATSEQBAIJ;
 21:   Mat         A,*B;
 22:   int         ierr,start=0,size;
 23:   IS          isrow,iscol;
 24:   PetscTruth  flg;

 26:   PetscInitialize(&argc,&args,(char *)0,help);


 29:   PetscOptionsGetString(PETSC_NULL,"-fin",fin,127,&flg);
 30:   if (!flg) SETERRQ(1,"Must indicate binary file with the -fin option");
 31:   PetscViewerBinaryOpen(PETSC_COMM_SELF,fin,PETSC_FILE_RDONLY,&fdin);

 33:   PetscOptionsGetString(PETSC_NULL,"-fout",fout,127,&flg);
 34:   if (!flg) {PetscPrintf(PETSC_COMM_WORLD,"Writing submatrix to file : %s\n",fout);}
 35:   PetscViewerBinaryOpen(PETSC_COMM_SELF,fout,PETSC_FILE_CREATE,&fdout);

 37:   MatLoad(fdin,mtype,&A);
 38:   PetscViewerDestroy(fdin);
 39: 
 40:   MatGetSize(A,&size,&size);
 41:   size /= 2;
 42:   PetscOptionsGetInt(PETSC_NULL,"-start",&start,PETSC_NULL);
 43:   PetscOptionsGetInt(PETSC_NULL,"-size",&size,PETSC_NULL);
 44: 
 45:   ISCreateStride(PETSC_COMM_SELF,size,start,1,&isrow);
 46:   ISCreateStride(PETSC_COMM_SELF,size,start,1,&iscol);
 47:   MatGetSubMatrices(A,1,&isrow,&iscol,MAT_INITIAL_MATRIX,&B);
 48:   MatView(B[0],fdout);

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

 56:   MatDestroy(A);
 57:   MatDestroy(B[0]);
 58:   VecDestroy(b);
 59:   PetscFree(B);
 60:   ISDestroy(iscol);
 61:   ISDestroy(isrow);
 62:   PetscFinalize();
 63:   return 0;
 64: }