---
name: "fast_normalize"
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/fast_normalize"
---

# fast\_normalize(3clc)

Normal vector length 1.

## NAME

fast\_normalize - Normal vector length 1.

##

**floatn fast\_normalize(floatn** *p***);**

## DESCRIPTION

Returns a vector in the same direction as *p* but with a length of 1. **fast\_normalize** is computed as:

```
p * sqrt(3clc)(p.x2 + p.y2 +...)
```

The result shall be within 8192 ulps error from the infinitely precise result of:

```
if ( any(3clc)(p == 0.0f))
result = p;
else
result = p /  sqrt(3clc)(p.x2 + p.y2 +...);
```

with the following exceptions:

 1\. If the sum of squares is greater than **FLT\_MAX** then the value of the floating-point values in the result vector are undefined.

 2\. If the sum of squares is less than **FLT\_MIN** then the implementation may return back *p*.

 3\. If the device is in 'denorms are flushed to zero' mode, individual operand elements with magnitude less than [**sqrt**(3clc)](/sqrt/3clc.md)(**FLT\_MIN**) may be flushed to zero before proceeding with the calculation.

## NOTES

Built-in geometric functions operate component-wise. The description is per-component. **float***n* is **float**, **float2**, **float3**, or **float4** and **double***n* is **double**, **double2**, **double3**, or **double4**. The built-in geometric functions are implemented using the round to nearest even rounding mode.

The geometric functions can be implemented using contractions such as [**mad**(3clc)](/mad/3clc.md) or [**fma**(3clc)](/fma/3clc.md).

## SPECIFICATION

**OpenCL Specification**\[1\]

## SEE ALSO

[**geometricFunctions**(3clc)](/geometricFunctions/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 262, section 6.12.5 - Geometric Functions