#include <stdio.h>

#include <math.h>

#include <gsl/gsl_integration.h>

#include <gsl/gsl_sf_gamma.h>

double

f(double x, void * params)

{

  int m = *(int *) params;

  double f = gsl_pow_int(x, m) + 1.0;

  return f;

}

int

main (int argc, char *argv[])

{

  gsl_integration_fixed_workspace * w;

  const gsl_integration_fixed_type * T = gsl_integration_fixed_hermite;

  int m = 10;

  int n = 6;

  double expected, result;

  gsl_function F;

  if (argc > 1)

    m = atoi(argv[1]);

  if (argc > 2)

    n = atoi(argv[2]);

  w = gsl_integration_fixed_alloc(T, n, 0.0, 1.0, 0.0, 0.0);

  F.function = &f;

  F.params = &m;

  gsl_integration_fixed(&F, &result, w);

  if (m % 2 == 0)

    expected = M_SQRTPI + gsl_sf_gamma(0.5*(1.0 + m));

  else

    expected = M_SQRTPI;

  printf ("m               = %d\n", m);

  printf ("intervals       = %zu\n", gsl_integration_fixed_n(w));

  printf ("result          = % .18f\n", result);

  printf ("exact result    = % .18f\n", expected);

  printf ("actual error    = % .18f\n", result - expected);

  gsl_integration_fixed_free (w);

  return 0;

}