__k_lgamma
p = log(pi / (fabs(t) * z)) - __k_lgamma(z, signgamp);
g = __k_lgamma(x, &signgam);
g = __k_lgamma(x, &signgam);
g = __k_lgamma(x, signgamp);
extern double __k_lgamma __P((double, int *));
y = (float)__k_lgamma((double)x, &signgamf);
return ((float)__k_lgamma((double)x, signgamfp));