---
name: "lgamma"
section: "3clc"
platform: "linux"
package: "opencl-1.2-man-doc"
version: "1.0~svn33624-5.1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/lgamma/3clc"
---

# lgamma(3clc)

Log gamma functions.

## NAME

lgamma,\_lgamma\_r - Log gamma functions.

##

**gentype lgamma(gentype** *x***);**

**floatn lgamma\_r(floatn** *x***, \_\_global intn \****signp***);**

**floatn lgamma\_r(floatn** *x***, \_\_local intn \****signp***);**

**floatn lgamma\_r(floatn** *x***, \_\_private intn \****signp***);**

**float lgamma\_r(float** *x***, \_\_global int \****signp***);**

**float lgamma\_r(float** *x***, \_\_local int \****signp***);**

**float lgamma\_r(float** *x***, \_\_private int \****signp***);**

**doublen lgamma\_r(doublen** *x***, \_\_global intn \****signp***);**

**doublen lgamma\_r(doublen** *x***, \_\_local intn \****signp***);**

**doublen lgamma\_r(doublen** *x***, \_\_private intn \****signp***);**

**double lgamma\_r(double** *x***, \_\_global int \****signp***);**

**double lgamma\_r(double** *x***, \_\_local int \****signp***);**

**double lgamma\_r(double** *x***, \_\_private int \****signp***);**

**halfn lgamma\_r(halfn** *x***, \_\_global intn \****signp***);**

**halfn lgamma\_r(halfn** *x***, \_\_local intn \****signp***);**

**halfn lgamma\_r(halfn** *x***, \_\_private intn \****signp***);**

**half lgamma\_r(half** *x***, \_\_global int \****signp***);**

**half lgamma\_r(half** *x***, \_\_local int \****signp***);**

**half lgamma\_r(half** *x***, \_\_private int \****signp***);**

## DESCRIPTION

Returns the natural logarithm of the absolute value of the gamma function. The sign of the gamma function is returned in the *signp* argument of the **lgamma\_r**.

An application that wants to use **half** and **half***n* types will need to include the #pragma OPENCL EXTENSION [**cl\_khr\_fp16**(3clc)](/cl_khr_fp16/3clc.md) : enable directive. If extended with [**cl\_khr\_fp16**(3clc)](/cl_khr_fp16/3clc.md), generic type name **gentype** also includes **half** and **half{2\|3\|4\|8\|16}**.

## NOTES

The vector versions of the math functions operate component-wise. The description is per-component.

The built-in math functions are not affected by the prevailing rounding mode in the calling environment, and always return the same value as they would if called with the round to nearest even rounding mode.

The built-in math functions take scalar or vector arguments. For any specific use of these function, the actual type has to be the same for all arguments and the return type unless otherwise specified.

The generic type name **gentype** is used to indicate that the function can take **float**, **float2**, **float3**, **float4**, **float8**, **float16**, **double**, **double2**, **double3**, **double4**, **double8**, or **double16** as the type for the arguments.

If extended with [**cl\_khr\_fp16**(3clc)](/cl_khr_fp16/3clc.md), generic type name **gentype** may indicate **half** and **half{2\|3\|4\|8\|16}** as arguments and return values.

The generic type name **gentypef** is used to indicate that the function can take **float**, **float2**, **float3**, **float4**, **float8**, or **float16** as the type for the arguments.

The generic type name **gentyped** is used to indicate that the function can take **double**, **double2**, **double3**, **double4**, **double8**, or **double16** as the type for the arguments.

## SPECIFICATION

**OpenCL Specification**\[1\]

## SEE ALSO

[**mathFunctions**(3clc)](/mathFunctions/3clc.md)

## AUTHORS

**The Khronos Group**

## COPYRIGHT

Copyright © 2007-2011 The Khronos Group Inc.\
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and/or associated documentation files (the "Materials"), to deal in the Materials without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Materials, and to permit persons to whom the Materials are furnished to do so, subject to the condition that this copyright notice and permission notice shall be included in all copies or substantial portions of the Materials.

## NOTES

- 1\.

  OpenCL Specification

  page 244, section 6.12.2 - Math Functions