Actual source code: ex14.c

  1: /*$Id: ex14.c,v 1.19 2001/08/07 03:03:07 balay Exp $*/

  3: static char help[] = "Tests MatGetRow() and MatRestoreRow().n";

 5:  #include petscmat.h

  7: int main(int argc,char **args)
  8: {
  9:   Mat    C;
 10:   int    i,j,m = 5,n = 5,I,J,ierr,*idx,nz;
 11:   PetscScalar v,*values;

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

 15:   /* Create the matrix for the five point stencil, YET AGAIN */
 16:   MatCreate(PETSC_COMM_SELF,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n,&C);
 17:   MatSetFromOptions(C);
 18:   for (i=0; i<m; i++) {
 19:     for (j=0; j<n; j++) {
 20:       v = -1.0;  I = j + n*i;
 21:       if (i>0)   {J = I - n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 22:       if (i<m-1) {J = I + n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 23:       if (j>0)   {J = I - 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 24:       if (j<n-1) {J = I + 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 25:       v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
 26:     }
 27:   }
 28:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 29:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 30:   MatView(C,PETSC_VIEWER_STDOUT_SELF);

 32:   for (i=0; i<m*n; i++) {
 33:     MatGetRow(C,i,&nz,&idx,&values);
 34: #if defined(PETSC_USE_COMPLEX)
 35:     for (j=0; j<nz; j++) {PetscPrintf(PETSC_COMM_SELF,"%d %g ",idx[j],PetscRealPart(values[j]));}
 36: #else
 37:     for (j=0; j<nz; j++) {PetscPrintf(PETSC_COMM_SELF,"%d %g ",idx[j],values[j]);}
 38: #endif
 39:     PetscPrintf(PETSC_COMM_SELF,"n");
 40:     MatRestoreRow(C,i,&nz,&idx,&values);
 41:   }

 43:   MatDestroy(C);
 44:   PetscFinalize();
 45:   return 0;
 46: }