using static System.Math;
public static partial class math{

/*
public static double gamma(double x){
/// single precision gamma function (Wikipedia)
	if(x<0 )return PI/Sin(PI*x)/gamma(-x+1);
	if(x<10)return gamma(x+1)/x; // move argument up
	const double a=1.0/12, b=1.0/12, c=59.0/360, d=29.0/60;
	double lngamma=x*Log(x)-x+0.5*Log(2*PI/x)
		+(a+(b+(c+d/(x+4))/(x+3))/(x+2))/(x+1);
	return Exp(lngamma);
}
*/

public static double gamma(double x){
/// single precision gamma function (Gergo Nemes, from Wikipedia)
	if(x<0)return PI/Sin(PI*x)/gamma(1-x);
	if(x<9)return gamma(x+1)/x; // move argument up
	double lngamma=x*Log(x+1/(12*x-1/x/10))-x+Log(2*PI/x)/2;
	return Exp(lngamma);
}

}//math