DoubleFactorial {TreeTools} | R Documentation |
Double factorial
Description
Calculate the double factorial of a number, or its logarithm.
Usage
DoubleFactorial(n)
DoubleFactorial64(n)
LnDoubleFactorial(n)
Log2DoubleFactorial(n)
LogDoubleFactorial(n)
LnDoubleFactorial.int(n)
LogDoubleFactorial.int(n)
Arguments
n |
Vector of integers. |
Value
Returns the double factorial, n * (n - 2) * (n - 4) * (n - 6) * ...
Functions
-
DoubleFactorial64()
: Returns the exact double factorial as a 64-bitinteger64
, forn
< 34. -
LnDoubleFactorial()
: Returns the logarithm of the double factorial. -
Log2DoubleFactorial()
: Returns the logarithm of the double factorial. -
LnDoubleFactorial.int()
: Slightly faster, when x is known to be length one and below 50001
Author(s)
Martin R. Smith (martin.smith@durham.ac.uk)
See Also
Other double factorials:
doubleFactorials
,
logDoubleFactorials
Examples
DoubleFactorial (-4:0) # Return 1 if n < 2
DoubleFactorial (2) # 2
DoubleFactorial (5) # 1 * 3 * 5
exp(LnDoubleFactorial.int (8)) # log(2 * 4 * 6 * 8)
DoubleFactorial64(31)
[Package TreeTools version 1.12.0 Index]