double gsl_cdf_chisq_Qinv (const double Q, const double nu) { return gsl_cdf_gamma_Qinv (Q, nu / 2, 2.0); }
int main(int argc, char** argv) { printf("%1.20lf\n", gsl_cdf_gamma_Qinv(0.5, 1.0, 1.0)); return 0; }