Actual source code: ex33.c

petsc-3.12.1 2019-10-22
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  2: static char help[] = "Tests the routines VecScatterCreateToAll(), VecScatterCreateToZero()\n\n";

  4:  #include <petscvec.h>

  6: int main(int argc,char **argv)
  7: {
  8:   PetscInt       n = 3,i,len,start,end;
 10:   PetscMPIInt    size,rank;
 11:   PetscScalar    value,*yy;
 12:   Vec            x,y,z,y_t;
 13:   VecScatter     toall,tozero;

 15:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 16:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 17:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

 19:   /* create two vectors */
 20:   VecCreateMPI(PETSC_COMM_WORLD,PETSC_DECIDE,size*n,&x);

 22:   /* each processor inserts its values */

 24:   VecGetOwnershipRange(x,&start,&end);
 25:   for (i=start; i<end; i++) {
 26:     value = (PetscScalar) i;
 27:     VecSetValues(x,1,&i,&value,INSERT_VALUES);
 28:   }
 29:   VecAssemblyBegin(x);
 30:   VecAssemblyEnd(x);
 31:   VecView(x,PETSC_VIEWER_STDOUT_WORLD);

 33:   VecScatterCreateToAll(x,&toall,&y);
 34:   VecScatterBegin(toall,x,y,INSERT_VALUES,SCATTER_FORWARD);
 35:   VecScatterEnd(toall,x,y,INSERT_VALUES,SCATTER_FORWARD);
 36:   VecScatterDestroy(&toall);

 38:   /* Cannot view the above vector with VecView(), so place it in an MPI Vec
 39:      and do a VecView() */
 40:   VecGetArray(y,&yy);
 41:   VecGetLocalSize(y,&len);
 42:   VecCreateMPIWithArray(PETSC_COMM_WORLD,1,len,PETSC_DECIDE,yy,&y_t);
 43:   VecView(y_t,PETSC_VIEWER_STDOUT_WORLD);
 44:   VecDestroy(&y_t);
 45:   VecRestoreArray(y,&yy);

 47:   VecScatterCreateToAll(x,&tozero,&z);
 48:   VecScatterBegin(tozero,x,z,INSERT_VALUES,SCATTER_FORWARD);
 49:   VecScatterEnd(tozero,x,z,INSERT_VALUES,SCATTER_FORWARD);
 50:   VecScatterDestroy(&tozero);
 51:   if (!rank) {
 52:     VecView(z,PETSC_VIEWER_STDOUT_SELF);
 53:   }
 54:   VecDestroy(&z);

 56:   VecScatterCreateToZero(x,&tozero,&z);
 57:   VecScatterBegin(tozero,x,z,INSERT_VALUES,SCATTER_FORWARD);
 58:   VecScatterEnd(tozero,x,z,INSERT_VALUES,SCATTER_FORWARD);
 59:   VecScatterDestroy(&tozero);
 60:   VecDestroy(&z);

 62:   VecDestroy(&x);
 63:   VecDestroy(&y);

 65:   PetscFinalize();
 66:   return ierr;
 67: }



 71: /*TEST

 73:    test:
 74:       nsize: 4

 76: TEST*/