Routines (alphabetical) > Routines: L > LNGAMMA

# LNGAMMA

The LNGAMMA function returns the logarithm of the gamma function of Z.

## Examples

To find the logarithm of the gamma function of 0.5 and store the result in variable A, enter:

A = LNGAMMA(0.5)

## Syntax

Result = LNGAMMA(Z)

## Return Value

For negative integers, LNGAMMA returns the correct value of Infinity. If Z is double-precision, the result is double-precision (either double or double complex), otherwise the result is single-precision (either float or complex).

Note: For negative nonintegers, LNGAMMA will also return Infinity. To compute the actual LNGAMMA of a negative noninteger, you should convert your input to complex first.

## Arguments

### Z

The expression for which the logarithm of the gamma function will be evaluated. Z may be complex.

## Keywords

### Thread Pool Keywords

This routine is written to make use of IDL’s thread pool, which can increase execution speed on systems with multiple CPUs. The values stored in the !CPU system variable control whether IDL uses the thread pool for a given computation. In addition, you can use the thread pool keywords TPOOL_MAX_ELTS, TPOOL_MIN_ELTS, and TPOOL_NOTHREAD to override the defaults established by !CPU for a single invocation of this routine.

## Version History

Pre 4.0 | Introduced
5.6 | Z argument accepts complex input

## See Also

BETA, GAMMA, IBETA, IGAMMA