#include <stdio.h>

#include <gsl/gsl_math.h>

#include <gsl/gsl_deriv.h>

double f (double x, void * params)

{

  (void)(params); /* avoid unused parameter warning */

  return pow (x, 1.5);

}

int

main (void)

{

  gsl_function F;

  double result, abserr;

  F.function = &f;

  F.params = 0;

  printf ("f(x) = x^(3/2)\n");

  gsl_deriv_central (&F, 2.0, 1e-8, &result, &abserr);

  printf ("x = 2.0\n");

  printf ("f'(x) = %.10f +/- %.10f\n", result, abserr);

  printf ("exact = %.10f\n\n", 1.5 * sqrt(2.0));

  gsl_deriv_forward (&F, 0.0, 1e-8, &result, &abserr);

  printf ("x = 0.0\n");

  printf ("f'(x) = %.10f +/- %.10f\n", result, abserr);

  printf ("exact = %.10f\n", 0.0);

  return 0;

}