Next: The Flat (Uniform) Distribution, Previous: The Levy skew alpha-Stable Distribution, Up: Random Number Distributions [Index]

- Function:
*double***gsl_ran_gamma***(const gsl_rng **`r`, double`a`, double`b`) -
This function returns a random variate from the gamma distribution. The distribution function is,

p(x) dx = {1 \over \Gamma(a) b^a} x^{a-1} e^{-x/b} dx

for

*x > 0*.The gamma distribution with an integer parameter

`a`is known as the Erlang distribution.The variates are computed using the Marsaglia-Tsang fast gamma method. This function for this method was previously called

`gsl_ran_gamma_mt`

and can still be accessed using this name.

- Function:
*double***gsl_ran_gamma_knuth***(const gsl_rng **`r`, double`a`, double`b`) This function returns a gamma variate using the algorithms from Knuth (vol 2).

- Function:
*double***gsl_ran_gamma_pdf***(double*`x`, double`a`, double`b`) This function computes the probability density

*p(x)*at`x`for a gamma distribution with parameters`a`and`b`, using the formula given above.

- Function:
*double***gsl_cdf_gamma_P***(double*`x`, double`a`, double`b`) - Function:
*double***gsl_cdf_gamma_Q***(double*`x`, double`a`, double`b`) - Function:
*double***gsl_cdf_gamma_Pinv***(double*`P`, double`a`, double`b`) - Function:
*double***gsl_cdf_gamma_Qinv***(double*`Q`, double`a`, double`b`) These functions compute the cumulative distribution functions

*P(x)*,*Q(x)*and their inverses for the gamma distribution with parameters`a`and`b`.