Actual source code: ex2.c

petsc-3.12.1 2019-10-22
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  2: static char help[] = "Tests vector scatter-gather operations.  Input arguments are\n\
  3:   -n <length> : vector length\n\n";

  5:  #include <petscvec.h>

  7: int main(int argc,char **argv)
  8: {
 10:   PetscInt       n   = 5,idx1[2] = {0,3},idx2[2] = {1,4};
 11:   PetscScalar    one = 1.0,two = 2.0;
 12:   Vec            x,y;
 13:   IS             is1,is2;
 14:   VecScatter     ctx = 0;

 16:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 17:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);

 19:   /* create two vector */
 20:   VecCreateSeq(PETSC_COMM_SELF,n,&x);
 21:   VecDuplicate(x,&y);

 23:   /* create two index sets */
 24:   ISCreateGeneral(PETSC_COMM_SELF,2,idx1,PETSC_COPY_VALUES,&is1);
 25:   ISCreateGeneral(PETSC_COMM_SELF,2,idx2,PETSC_COPY_VALUES,&is2);

 27:   VecSet(x,one);
 28:   VecSet(y,two);
 29:   VecScatterCreate(x,is1,y,is2,&ctx);
 30:   VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 31:   VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);

 33:   VecView(y,PETSC_VIEWER_STDOUT_SELF);

 35:   VecScatterBegin(ctx,y,x,INSERT_VALUES,SCATTER_FORWARD);
 36:   VecScatterEnd(ctx,y,x,INSERT_VALUES,SCATTER_FORWARD);
 37:   VecScatterDestroy(&ctx);

 39:   PetscPrintf(PETSC_COMM_SELF,"-------\n");
 40:   VecView(x,PETSC_VIEWER_STDOUT_SELF);

 42:   ISDestroy(&is1);
 43:   ISDestroy(&is2);

 45:   VecDestroy(&x);
 46:   VecDestroy(&y);

 48:   PetscFinalize();
 49:   return ierr;
 50: }

 52: /*TEST

 54:      test:

 56: TEST*/