Investment Studio > Expressions > Functions > Math & Trig > FACTDOUBLE

float factdouble(integer argument)

Returns the double factorial of the argument. The argument must be a natural number (i.e. > 0).

If the argument is even, the double factorial is argument * (argument - 2) * ... * 4 * 2.

If the argument is odd, the double factorial is argument * (argument - 2) * ... * 3 * 1.

Example

=factdouble(6)

equals 6 * 4 * 2 = 48, while

=factdouble(7)

equals 7 * 5 * 3 * 1 = 105.

See also binomdist, combin, critbinom, fact, hypgeomdist, negbinomdist, permut.