public static double Value(int n)
{
Assertion.NonNegative(nameof(n), n);
if (n <= 20)
{
long value = 1;
for (long i = 1; i <= n; i++)
{
value *= i;
}
return(value);
}
return(GammaFunction.Value(n + 1));
}
/// <summary>
/// Complete beta function B(a,b)
/// </summary>
public static double CompleteValue(double a, double b)
{
return(GammaFunction.Value(a) * GammaFunction.Value(b) / GammaFunction.Value(a + b));
}