Random numbers from the gamma distribution
x = rgamma(n,a [,s])
positive integer or a vector [lig,col] of integers
positive reals.
n-vector or a n-matrix of random numbers chosen from Gamma distribution with parameter a
Random numbers from the gamma distribution (inversion method) The gamma density function with parameter a is :
x --> (s^a)*x.^(a-1)exp(-s*x)./Gamma(a)1_{x>=0}