[Scilab-Dev] Incomplete Gamma function

[calixte]

Le jeudi 29 juillet 2010 à 18:58 +0200, calixte a écrit :
> Hello Mathieu,
> 
> gammainc(x,y) is equivalent to 1-cdfpoi("PQ",y-1,x) or gammainc(x,y)=Q
> where Q is obtained with [P,Q]=cdfpoi("PQ",y-1,x).
> Since cdfpoi is a built-in function, the performances are better :
> 

Or better gammainc(x,y) is equivalent to cdfgam("PQ",x,y,1)...

'help cdfgam' should help you.

Calixte

> -->tic();for i=1:1000;gammainc(3.1,4.2);end;toc()
>  ans  =
>  
>     1.144  
>  
> -->tic();for i=1:1000;1-cdfpoi("PQ",3.2,3.1);end;toc()
>  ans  =
>  
>     0.017
> 
> Best regards,
> 
> Calixte
> 
> Le jeudi 29 juillet 2010 à 01:37 +0200, OLIVIER Mathieu a écrit :
> > Hi,
> > 
> > I needed the Incomplete Gamma function, as it was not available in 
> > Scilab, I've developed my own one, based onto the NUMERICAL RECIPES.
> > 
> > This functions works and gives sames results than the one from MATLAB 
> > (with my own tests).
> > 
> > So I would like to submit this function, perhaps this one could be added 
> > in a future version of Scilab or help to made a "Scilab version".
> > 
> > Regards
> > 
> > Mathieu OLIVIER
> > 
> 
>