fact

Description

Factorial.

Arguments and Return Values

Arguments: One numeric array

Return Value: The factorial of the input

Usage

Syntax: fact(x)

'x' - a numeric array whose value is an integer or half-integer x, such that -0.5 ≤ x ≤ 34

fact(n) = n! = n*(n-1)*(n-2)*...*2*1 for integers; 0! = 1

n! = n*(n-1)*(n-2)*...0.5*fact(-0.5) for half-integers; (-0.5)! = √π

Return format:

int, when all elements of input are integers less than or equal to 12 (any format)

float, when some elements of input are half-integer floats, or when the maximum value of the input is greater than 12

double, when some elements of input are half-integer doubles

In general, the function returns the simplest format that can accurately represent the value of the factorial.

If no arguments are input, fact() prints its description, as shown below.

Examples

dv> fact()

Factorial
fact(n), integers or half-integers -0.5 <= n <= 34
Works for arrays
S.Marshall 02-17-2008

0
dv> fact(create(7))
7x1x1 array of int, bsq format [28 bytes]
1       1       2       6       24      120     720
dv> fact(-0.5//0.//0.5//1.//1.5//2.)
6x1x1 array of float, bsq format [24 bytes]
1.77245 1.00000 0.886227        1.00000 1.32934 2.00000
dv> fact(-1)

Input must be integers or half-integers -0.5 <= n <= 34

0
dv> fact(33)
8.68332e+36
dv> fact(34)
2.95233e+38
dv> fact(35)

Input must be integers or half-integers -0.5 <= n <= 34

0