Documentation/Calc Functions/FACTDOUBLE
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Function name:
FACTDOUBLE
Category:
Add-in
Summary:
Calculates the double factorial of a non-negative integer value. If n is an even positive integer, its double factorial is the product of all even integers in the range [2, n]; if n is an odd positive integer, its double factorial is the product of all odd integers in the range [1, n]. The double factorial of n is usually denoted by n!!.
Syntax:
FACTDOUBLE(Number)
Returns:
Returns a positive integer, which is the double factorial of the supplied number.
Arguments:
Number is a non-negative integer, or a reference to the cell containing that integer, whose double factorial value is to be calculated.
- If Number is non-numeric, then FACTDOUBLE reports a #VALUE! error.
- If Number is a non-integer value, then FACTDOUBLE truncates it to an integer.
- If, after any truncation, Number is less than 0 or greater than 300, then FACTDOUBLE reports an invalid argument error (Err:502).
Additional details:
By definition FACTDOUBLE(0) = 1.
For an even positive integer ne:
[math]\displaystyle{ \text{FACTDOUBLE}(n_e)~=~n_e\times(n_e-2)\times(n_e-4)\times...\times\:4\:\times\:2 }[/math]
For an odd positive integer no:
[math]\displaystyle{ \text{FACTDOUBLE}(n_o)~=~n_o\times(n_o-2)\times(n_o-4)\times...\times\:3\:\times\:1 }[/math]
More information can be found at Wikipedia's Double factorial page.
Examples:
| Formula | Description | Returns |
|---|---|---|
| =FACTDOUBLE(1) | Here the function calculates 1!!, returning the value 1. | 1 |
| =FACTDOUBLE(2) | Here the function calculates 2!!, returning the value 2. | 2 |
| =FACTDOUBLE(3) | Here the function calculates 3!!, returning the value 3 (3 * 1). | 3 |
| =FACTDOUBLE(4) | Here the function calculates 4!!, returning the value 8 (4 * 2). | 8 |
| =FACTDOUBLE(5) | Here the function calculates 5!!, returning the value 15 (5 * 3 * 1). | 15 |
| =FACTDOUBLE(6) | Here the function calculates 6!!, returning the value 48 (6 * 4 * 2). | 48 |
| =FACTDOUBLE(7) | Here the function calculates 7!!, returning the value 105 (7 * 5 * 3 * 1). | 105 |
| =FACTDOUBLE(D1) where cell D1 contains the value 8. | Here the function calculates 8!!, returning the value 384 (8 * 6 * 4 * 2). | 384 |
Related LibreOffice functions:
ODF standard:
Related (or similar) Excel functions:
FACTDOUBLE