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

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

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

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

 34:   for (i=0; i<m*n; i++) {
 35:     MatGetRow(C,i,&nz,&idx,&values);
 36: #if defined(PETSC_USE_COMPLEX)
 37:     for (j=0; j<nz; j++) {PetscPrintf(PETSC_COMM_SELF,"%d %g ",idx[j],PetscRealPart(values[j]));}
 38: #else
 39:     for (j=0; j<nz; j++) {PetscPrintf(PETSC_COMM_SELF,"%d %g ",idx[j],values[j]);}
 40: #endif
 41:     PetscPrintf(PETSC_COMM_SELF,"\n");
 42:     MatRestoreRow(C,i,&nz,&idx,&values);
 43:   }

 45:   MatDestroy(C);
 46:   PetscFinalize();
 47:   return 0;
 48: }