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
b...@fencepost:~/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'
b...@fencepost:~/tmp$ gcc -Wall beta.c -lgsl -lgslcblas -lm # with #include
<gsl_sf.h>
b...@fencepost:~/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
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