Random: double gsl_ran_cauchy(const gsl_rng * r, double a)
This function returns a random variate from the Cauchy distribution with
scale parameter a. The probability distribution for Cauchy
random variates is,
p(x) dx = {1 \over a\pi (1 + (x/a)^2) } dx
for x in the range -\infty to +\infty. The Cauchy
distribution is also known as the Lorentz distribution.
Function: double gsl_ran_cauchy_pdf(double x, double a)
This function computes the probability density p(x) at x
for a Cauchy distribution with scale parameter a, using the formula
given above.