LGAMMA(3clc)

💖 LGAMMA, LGAMMA_R 💖

okay bestie, welcome to the OpenCL Manual entry for lgamma and lgamma_r — the log gamma girlies. this is section 3clc, and yes we are absolutely going to get into it ✨

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🌸 NAME 🌸

lgamma, lgamma_r — Log gamma functions. that's the whole vibe. 💅

and here's the full cast of signatures, no cap, every single one:

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);

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✨ DESCRIPTION ✨

so like, it returns the natural logarithm of the absolute value of the gamma function. that's the tea. 🫖

and the sign of the gamma function? that doesn't come back as the return value, bestie — it gets handed to you through the signp argument of the lgamma_r version. the way that works is genuinely iconic. 👑

real talk tho: if you wanna use half and halfn types, you're gonna need to include this directive:

#pragma OPENCL EXTENSION cl_khr_fp16(3clc) : enable

and if it gets extended with cl_khr_fp16(3clc), the generic type name gentype also includes half and half{2|3|4|8|16}. slay. 🦋

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📝 NOTES 📝

• The vector versions of the math functions operate component-wise. the description is per-component. so like, one component at a time, each living its own little life. ✨
• 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. periodt.
• The built-in math functions take scalar or vector arguments. for any specific use of these functions, the actual type has to be the same for all arguments and the return type unless otherwise specified. no mixing, bestie, it's giving monogamy. 💀
• 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), 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.

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🎀 SPECIFICATION 🎀

OpenCL Specification[1] — that's the source of truth, iykyk.

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👀 SEE ALSO 👀

• mathFunctions(3clc)

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👑 AUTHORS 👑

The Khronos Group. the icons themselves. 💜

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🌈 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.

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🧚 NOTES 🧚

1. OpenCL Specification page 244, section 6.12.2 - Math Functions

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okay that's the whole page, bestie, you ate that 🍓 — this was brought to you by The Khronos Group, dated 01/14/2021, and the original header said LGAMMA, LGAMMA_R(3clc). mwah. 💖✨