AngouriMath

Navigation

Home Quick start Wiki Almanac Research What's new Try Use Angouri.org GitHub Report a bug Contacts

← Back to list of members

DoubleFactorial(AngouriMath.Entity)

Method (no overloads)

Summary

The double factorial n!!: n (n - 2) (n - 4) ... down to 1 or 2

Parameter "n"

An integer, other than a negative even one

Returns

The DoubleFactorialf node

Remarks

0!! and (-1)!! are 1, a negative odd n follows from
n!! = (n + 2)!!/(n + 2), and off the integers it has no value. It is not (n!)!.
https://github.com/asc-community/AngouriMath/issues/2182

Example

using System;
using static AngouriMath.MathS;
            
Console.WriteLine(DoubleFactorial(7).Simplify());
Console.WriteLine(DoubleFactorial(8).Simplify());
Console.WriteLine(DoubleFactorial(-5).Simplify());

Prints

105
384
1/3

AngouriMath

Table of contents

AngouriMath

DoubleFactorial​(AngouriMath.​Entity)

DoubleFactorial(AngouriMath.Entity)