Re: [Bug-gsl] gsl_sf_beta_inc returns 0.0 all the time

[Andrew Schein]

Thank you, Brian.  I forgot "-Wall" which would have given me the relevant
information.

-Andy

On Thu, Dec 23, 2010 at 6:24 AM, Brian Gough <address@hidden> wrote:

> At Tue, 21 Dec 2010 21:38:03 -0800,
> Andrew Schein wrote:
> > Attached is a short program that attempts to reproduce a portion of the
> > incomplete beta curve for comparison against a plot shown in Numerical
> > Recipes in C++.  The numerical recipes plot varies x between (0,1) while
> > setting a=b=0.5.
> >
> > #include <stdio.h>
> > #include <gsl/gsl_rng.h>
> >
> > int main(int argc, char **argv) {
> >     long i;
> >     double x = 0.0;
> >     double a = 0.5;
> >     double b = 0.5;
> >     for (i=0; i < 10; i++) {
> >         x += 1.0/10.1;
> >         double from_gsl = gsl_sf_beta_inc(a,b,x);
> >         printf("a:%f b:%f x:%f betai(a,b,x):%f \n",a,b,x,from_gsl);
> >     }
> >     return 0;
> > }
>
> Hi.
>
> Thanks for the test program (much appreciated).  I noticed there's no
> #include <gsl_sf.h> -- with that it works for me, hopefully for you too.
>
> --
> Brian Gough
>
>
> address@hidden:~/tmp$ gcc -Wall beta.c -lgsl -lgslcblas -lm
> beta.c: In function 'main':
> beta.c:12:5: warning: implicit declaration of function 'gsl_sf_beta_inc'
>
> address@hidden:~/tmp$ gcc -Wall beta.c -lgsl -lgslcblas -lm # with #include
> <gsl_sf.h>
> address@hidden:~/tmp$ ./a.out
> a:0.500000 b:0.500000 x:0.099010 betai(a,b,x):0.203780
> a:0.500000 b:0.500000 x:0.198020 betai(a,b,x):0.293589
> a:0.500000 b:0.500000 x:0.297030 betai(a,b,x):0.366944
> a:0.500000 b:0.500000 x:0.396040 betai(a,b,x):0.433330
> a:0.500000 b:0.500000 x:0.495050 betai(a,b,x):0.496848
> a:0.500000 b:0.500000 x:0.594059 betai(a,b,x):0.560239
> a:0.500000 b:0.500000 x:0.693069 betai(a,b,x):0.626191
> a:0.500000 b:0.500000 x:0.792079 betai(a,b,x):0.698575
> a:0.500000 b:0.500000 x:0.891089 betai(a,b,x):0.785891
> a:0.500000 b:0.500000 x:0.990099 betai(a,b,x):0.936549
>
>


-- 
Andrew I. Schein
www.andrewschein.com