func Exponential(r *rng.GslRng, mu float64) float64 { return float64(C.gsl_ran_exponential((*C.gsl_rng)(unsafe.Pointer(r.Ptr())), C.double(mu))) }
func ExponentialRandomFloat64(rd *RNG, lambda float64) (x float64) { x = float64(C.gsl_ran_exponential(rd.g, C.double(lambda))) return x }
// Exponential returns a random variate from the exponential distribution with mean mu. func Exponential(rng RngState, mu float64) float64 { return float64(C.gsl_ran_exponential(rng.state, C.double(mu))) }