Hi All, gsl_sf_gegenpoly_1(0, x) returns (2 x) instead of 0. Here's a small example that reproduces the bug:
#include <stdio.h>
#include <gsl/gsl_sf_gegenbauer.h>
int main() {
printf("%g\n", gsl_sf_gegenpoly_1(0, 42));
return 0;
}
$ gcc test.c -lgsl -lgslcblas
$ ./a.out
84
Since C^{(\lambda)}_1(x) = 2 \lambda x (
http://mathworld.wolfram.com/GegenbauerPolynomial.html), gsl_sf_gegenpoly_1(0,
42) should return 0.
Best regards,
Victor
