Actual source code: ex8.c

  1: /*$Id: ex8.c,v 1.18 2001/08/07 03:03:07 balay Exp $*/

  3: static char help[] = "Tests automatic allocation of matrix storage space.\n\n";

 5:  #include petscmat.h

  9: int main(int argc,char **args)
 10: {
 11:   Mat         C;
 12:   int         i,j,m = 3,n = 3,I,J,ierr;
 13:   PetscScalar v;
 14:   MatInfo     info;

 16:   PetscInitialize(&argc,&args,(char *)0,help);
 17:   PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);
 18:   PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);

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

 37:   MatGetInfo(C,MAT_LOCAL,&info);
 38:   PetscPrintf(PETSC_COMM_SELF,"matrix nonzeros = %d, allocated nonzeros = %d\n",
 39:     (int)info.nz_used,(int)info.nz_allocated);

 41:   MatDestroy(C);
 42:   PetscFinalize();
 43:   return 0;
 44: }