public static Expression Factorial(Constant x)
{
if (x.IsInteger())
{
return(new Real(Factorial((BigInteger)(Real)x)));
}
else
{
throw new ArgumentException("Factorial cannot be called for non-integer value.");
}
}
public static Expression IsNatural(Constant x)
{
return(Constant.New(x.IsInteger() && (Real)x > 0));
}
public static Expression IsInteger(Constant x)
{
return(Constant.New(x.IsInteger()));
}