Actual source code: ex20.c

  1: /*$Id: ex20.c,v 1.23 2001/08/07 03:03:07 balay Exp $*/

  3: static char help[] = "Tests converting a matrix to another format with MatConvert().\n\n";

 5:  #include petscmat.h

  9: int main(int argc,char **args)
 10: {
 11:   Mat          C,A;
 12:   int          i,j,m = 5,n = 4,I,J,ierr,rank,size;
 13:   PetscScalar  v;
 14:   char         mtype[256];

 16:   PetscInitialize(&argc,&args,(char *)0,help);
 17:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

 19:   /* This example does not work correctly for np > 2 */
 20:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 21:   if (size > 2) SETERRQ(1,"Use np <= 2");

 23:  /* Create the matrix for the five point stencil, YET AGAIN */
 24:   MatCreate(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n,&C);
 25:   MatSetFromOptions(C);
 26:   for (i=0; i<m; i++) {
 27:     for (j=2*rank; j<2*rank+2; j++) {
 28:       v = -1.0;  I = j + n*i;
 29:       if (i>0)   {J = I - n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 30:       if (i<m-1) {J = I + n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 31:       if (j>0)   {J = I - 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 32:       if (j<n-1) {J = I + 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 33:       v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
 34:     }
 35:   }

 37:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 38:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 39:   PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO);
 40:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);
 41:   PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
 42:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);
 43: 
 44:   PetscStrcpy(mtype,MATSAME);
 45:   PetscOptionsGetString(PETSC_NULL,"-conv_mat_type",mtype,256,PETSC_NULL);
 46:   MatConvert(C,mtype,&A);
 47:   PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO);
 48:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);
 49:   PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
 50:   PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_IMPL);
 51:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);

 53:   /* Free data structures */
 54:   MatDestroy(A);
 55:   MatDestroy(C);

 57:   PetscFinalize();
 58:   return 0;
 59: }