Random: double gsl_ran_gumbel1(const gsl_rng * r, double a, double b)
This function returns a random variate from the Type-1 Gumbel
distribution. The Type-1 Gumbel distribution function is,
for @math{-\infty < x < \infty}.
Function: double gsl_ran_gumbel1_pdf(double x, double a, double b)
This function computes the probability density @math{p(x)} at x
for a Type-1 Gumbel distribution with parameters a and b,
using the formula given above.