Error with non_central_chi_squared::find_degrees_of_freedom when running with Valgrind #95

double find_chisq_df(double delta, double q, double p){
 // gives nu such that pchisq(q, nu, delta) = p
 return non_central_chi_squared::find_degrees_of_freedom(delta, q, p);
}

Error in function boost::math::non_central_chi_squared_distribution<long double>::non_central_chi_squared_distribution(long double,long double): Degrees of freedom argument is -nan, but must be > 0 !