Implementation of the Logarithm of the Gamma function

Dieter Kaiser wrote:
> Some days ago I have reported some work on the implementation of the Incomplete
> Beta function. By the way I have recognized that for the numerical evaluation of
> the Beta function the transformation to the Gamma function is used: 
> 
> beta(a,b)=gamma(a)*gamma(b)/gamma(a+b).
> 
> Especially for float arguments I think it is better to use the Logarithm of the
> Gamma function for evaluation:
> 
> beta(a,b)=exp(gamma_log(a)+gamma_log(b)-gamma(a+b)).

Note that using logs reduces the accuracy of the result, especially for
large arguments that otherwise would have fit in a float.

Don't know if this really matters or not.

Ray