[R] precision of gamma function

[Duncan Murdoch]

On 09/02/2011 10:23 AM, Chuse chuse wrote:
> Dear R users,
>
> I have to calculate gamma functions for negative numbers beyond -171.4.
> e.x. gamma(-500.4)
> I got following:
>
> >  gamma(-170.4)
> [1] -5.824625e-308
> >  gamma(-171.4)
> [1] 0
> Warning message:
> underflow occurred in 'gammafn'
>
> I have tried to use a recursion getting values a little futher -180.
> How could I solve this problem? Thank you beforehand.


Use the lgamma function.

Duncan Murdoch