Actual source code: ex18.c

petsc-3.7.5 2017-01-01
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  2: static char help[] = "Compares BLAS dots on different machines. Input\n\
  3: arguments are\n\
  4:   -n <length> : local vector length\n\n";

  6: #include <petscvec.h>

 10: int main(int argc,char **argv)
 11: {
 13:   PetscInt       n = 15,i;
 14:   PetscScalar    v;
 15:   Vec            x,y;

 17:   PetscInitialize(&argc,&argv,(char*)0,help);
 18:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 19:   if (n < 5) n = 5;


 22:   /* create two vectors */
 23:   VecCreateSeq(PETSC_COMM_SELF,n,&x);
 24:   VecCreateSeq(PETSC_COMM_SELF,n,&y);

 26:   for (i=0; i<n; i++) {
 27:     v    = ((PetscReal)i) + 1.0/(((PetscReal)i) + .35);
 28:     VecSetValues(x,1,&i,&v,INSERT_VALUES);
 29:     v   += 1.375547826473644376;
 30:     VecSetValues(y,1,&i,&v,INSERT_VALUES);
 31:   }
 32:   VecAssemblyBegin(y);
 33:   VecAssemblyEnd(y);

 35:   VecDot(x,y,&v);
 36:   PetscFPrintf(PETSC_COMM_WORLD,stdout,"Vector inner product %16.12e\n",v);

 38:   VecDestroy(&x);
 39:   VecDestroy(&y);

 41:   PetscFinalize();
 42:   return 0;
 43: }