/// <summary>Calculates the number of ways that a number of items may be permuted, which is equal to its factorial.</summary>
public static Integer CountPermutations(int n)
{
if (n < 1)
{
throw new ArgumentOutOfRangeException();
}
return(Integer.Factorial(n));
}
public ICalculonType Execute(ref ControllerState cs)
{
Integer input = (Integer)cs.stack.Pop();
if (input.data < 0)
{
cs.stack.Push(input);
return(new ErrorType(cs.Config.strings["FactorialNeg"]));
}
return(input.Factorial());
}