static char help[] = "Tests PetscIsCloseAtTol() routine.\n";

#include <petscsys.h>

PETSC_INTERN PetscReal zero;
PetscReal              zero = 0;
PETSC_INTERN PetscReal zero2;
PetscReal              zero2 = 0;

#define CALL(call) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "%s -> %s\n", #call, (call) ? "True" : "False"))

int main(int argc, char **argv)
{
  PetscReal eps      = PETSC_MACHINE_EPSILON;
  PetscReal neg_zero = PetscRealConstant(-0.0);
  PetscReal pos_zero = PetscRealConstant(+0.0);
  PetscReal neg_one  = PetscRealConstant(-1.0);
  PetscReal pos_one  = PetscRealConstant(+1.0);
  PetscReal neg_inf  = neg_one / zero;          /* -inf */
  PetscReal pos_inf  = pos_one / zero;          /* +inf */
  PetscReal x_nan    = zero2 / zero; /*  NaN */ /* some compilers may optimize out zero/zero and set x_nan = 1! */

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));

  CALL(PetscIsCloseAtTol(pos_zero, neg_zero, 0, 0));
  CALL(PetscIsCloseAtTol(pos_one, pos_one, 0, 0));
  CALL(PetscIsCloseAtTol(pos_one, neg_one, 0, 0));
  CALL(PetscIsCloseAtTol(pos_one, neg_one, 0, 2));
  CALL(PetscIsCloseAtTol(pos_one, neg_one, 2, 0));

  CALL(PetscIsCloseAtTol(pos_one + eps, pos_one, 0, 0));
  CALL(PetscIsCloseAtTol(pos_one - eps, pos_one, 0, 0));
  CALL(PetscIsCloseAtTol(pos_one + eps, pos_one, 0, 0));
  CALL(PetscIsCloseAtTol(pos_one - eps, pos_one, 0, 0));

  CALL(PetscIsCloseAtTol(pos_one + eps, pos_one, 0, eps));
  CALL(PetscIsCloseAtTol(pos_one - eps, pos_one, 0, eps));
  CALL(PetscIsCloseAtTol(pos_one + eps, pos_one, eps, 0));
  CALL(PetscIsCloseAtTol(pos_one - eps, pos_one, eps, 0));

  CALL(PetscIsCloseAtTol(pos_one + 2 * eps, pos_one, eps, 0));
  CALL(PetscIsCloseAtTol(pos_one - 2 * eps, pos_one, eps, 0));
  CALL(PetscIsCloseAtTol(pos_one + 2 * eps, pos_one, 0, eps));
  CALL(PetscIsCloseAtTol(pos_one - 2 * eps, pos_one, 0, eps));

  CALL(PetscIsCloseAtTol(neg_inf, neg_zero, 2, 2));
  CALL(PetscIsCloseAtTol(neg_inf, pos_zero, 2, 2));
  CALL(PetscIsCloseAtTol(neg_inf, neg_one, 2, 2));
  CALL(PetscIsCloseAtTol(neg_inf, pos_one, 2, 2));
  CALL(PetscIsCloseAtTol(neg_inf, neg_inf, 2, 2));
  CALL(PetscIsCloseAtTol(neg_inf, pos_inf, 2, 2));
  CALL(PetscIsCloseAtTol(neg_inf, x_nan, 2, 2));

  CALL(PetscIsCloseAtTol(pos_inf, neg_zero, 2, 2));
  CALL(PetscIsCloseAtTol(pos_inf, pos_zero, 2, 2));
  CALL(PetscIsCloseAtTol(pos_inf, neg_one, 2, 2));
  CALL(PetscIsCloseAtTol(pos_inf, pos_one, 2, 2));
  CALL(PetscIsCloseAtTol(pos_inf, neg_inf, 2, 2));
  CALL(PetscIsCloseAtTol(pos_inf, pos_inf, 2, 2));
  CALL(PetscIsCloseAtTol(pos_inf, x_nan, 2, 2));

  CALL(PetscIsCloseAtTol(x_nan, neg_zero, 2, 2));
  CALL(PetscIsCloseAtTol(x_nan, pos_zero, 2, 2));
  CALL(PetscIsCloseAtTol(x_nan, neg_one, 2, 2));
  CALL(PetscIsCloseAtTol(x_nan, pos_one, 2, 2));
  CALL(PetscIsCloseAtTol(x_nan, neg_inf, 2, 2));
  CALL(PetscIsCloseAtTol(x_nan, pos_inf, 2, 2));
  CALL(PetscIsCloseAtTol(x_nan, x_nan, 2, 2));

  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:
      args: -fp_trap 0
      output_file: output/ex39.out

TEST*/