extension function PDF.T1G (x, a, b) = gsl_ran_gumbel1_pdf (x, a, b);
no_opt extension function RV.T1G (a, b) = gsl_ran_gumbel1 (get_rng (), a, b);
// Type-2 Gumbel distribution.
extension function CDF.T2G (x, a, b) = gsl_cdf_gumbel2_P (x, a, b);
extension function IDF.T2G (P >= 0 && P <= 1, a, b)
extension function PDF.T1G (x, a, b) = gsl_ran_gumbel1_pdf (x, a, b);
no_opt extension function RV.T1G (a, b) = gsl_ran_gumbel1 (get_rng (), a, b);
// Type-2 Gumbel distribution.
extension function CDF.T2G (x, a, b) = gsl_cdf_gumbel2_P (x, a, b);
extension function IDF.T2G (P >= 0 && P <= 1, a, b)