Actual source code: ex18.c

petsc-3.8.4 2018-03-24
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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>

  8: int main(int argc,char **argv)
  9: {
 11:   PetscInt       n = 15,i;
 12:   PetscScalar    v;
 13:   Vec            x,y;

 15:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 16:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 17:   if (n < 5) n = 5;


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

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

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

 36:   VecDestroy(&x);
 37:   VecDestroy(&y);

 39:   PetscFinalize();
 40:   return ierr;
 41: }