## table of contents

LOG, LOG2, LOG10, LO(3clc) | OpenCL Manual | LOG, LOG2, LOG10, LO(3clc) |

# NAME¶

log,_log2,_log10,_log1p,_logb - Logarithm functions.# ¶

**gentype log(gentype ****);**

**gentype log2(gentype ****);**

**gentype log10(gentype ****);**

**gentype log1p(gentype ***x***);**

**gentype logb(gentype ***x***);**

**gentype half_log(gentype ***x***);**

**gentype half_log2(gentype ***x***);**

**gentype half_log10(gentype ***x***);**

**gentype native_log(gentype ***x***);**

**gentype native_log2(gentype ***x***);**

**gentype
native_log10(gentype ***x***);**

# DESCRIPTION¶

**log**computes natural logarithm.

**log2** computes a base 2 logarithm.

**log10** computes a base 10 logarithm.

**log1p** computes loge(1.0 + *x*).

**logb** computes the exponent of *x*, which is the
integral part of logr |*x*|.

**half_log** computes natural logarithm.

**half_log2** computes a base 2 logarithm.

**half_log10** computes a base 10 logarithm.

**native_log** computes natural logarithm over an
implementation-defined range. The maximum error is
implementation-defined.

**native_log2** computes a base 2 logarithm over an
implementation-defined range. The maximum error is
implementation-defined.

**native_log10** computes a base 10 logarithm over an
implementation-defined range. The maximum error is
implementation-defined.

# 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), 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.

Functions with the **half_** prefix are implemented with a
minimum of 10-bits of accuracy i.e. an ULP value less than or equal to 8192
ulp.

Functions with the **native__** prefix may map to one or more
native device instructions and will typically have better performance
compared to the corresponding functions (without the **native__**
prefix). The accuracy (and in some cases the input range(s)) of these
functions is implementation-defined.

# SPECIFICATION¶

**OpenCL Specification**[1]

# SEE ALSO¶

**mathFunctions**(3clc)

# 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

06/18/2014 | The Khronos Group |