The Flat (Uniform) Distribution

Random: double gsl_ran_flat (const gsl_rng * r, double a, double b)
This function returns a random variate from the flat (uniform) distribution from a to b. The distribution is,

p(x) dx = {1 \over (b-a)} dx

if a <= x < b and 0 otherwise.

Function: double gsl_ran_flat_pdf (double x, double a, double b)
This function computes the probability density p(x) at x for a uniform distribution from a to b, using the formula given above.