#include "genlib.h"
#include <math.h>
#include <stdio.h>

/*gamma covariance function*/
double gammf(double h, double alpha)
{
    float delta;
    double z;

    delta = pow(20., 1. / alpha) - 1.;
    z = 1. / (double)(pow(1. + h * delta, alpha));
    return (z);
}