// How to control precision in VecView ?
//
// ~> g++ -o vecViewPrecision.exe vecViewPrecision.cpp -lpetsc -lm
// ~> mpirun -n 5 vecViewPrecision.exe

#include <iostream>
#include "petsc.h"

int main(int argc,char **argv) {
  PetscInitialize(&argc, &argv, NULL, NULL);
  int size = 0; MPI_Comm_size(MPI_COMM_WORLD, &size);
  int rank = 0; MPI_Comm_rank(MPI_COMM_WORLD, &rank);

  Vec v;
  VecCreateMPI(PETSC_COMM_WORLD, 2, 2*size, &v);

  double value = 1.23456789;
  double coef = (rank%2 == 0) ? 1.e-6 : 1.e+6; // Big/small values
  VecSetValue(v, 2*rank+0,  rank*value*coef, INSERT_VALUES);
  VecSetValue(v, 2*rank+1, -rank/value/coef, INSERT_VALUES);
  VecAssemblyBegin(v); VecAssemblyEnd(v);

  VecView(v, PETSC_VIEWER_STDOUT_WORLD);

  PetscFinalize();
  return 0;
}