Random: double gsl_ran_exppow(const gsl_rng * r, double a, double b)
This function returns a random variate from the exponential power distribution
with scale parameter a and exponent b. The distribution is,
p(x) dx = {1 \over 2 a \Gamma(1+1/b)} \exp(-|x/a|^b) dx
for
x >= 0. For b = 1 this reduces to the Laplace
distribution. For b = 2 it has the same form as a gaussian
distribution, but with
a = \sqrt{2} \sigma.
Function: double gsl_ran_exppow_pdf(double x, double a, double b)
This function computes the probability density p(x) at x
for an exponential power distribution with scale parameter a
and exponent b, using the formula given above.