# RenderScript Vector Math Functions

## Overview

These functions interpret the input arguments as representation of vectors in n-dimensional space.

The precision of the mathematical operations on 32 bit floats is affected by the pragmas rs_fp_relaxed and rs_fp_full. See Mathematical Constants and Functions for details.

Different precision/speed tradeoffs can be achieved by using variants of the common math functions. Functions with a name starting with

• native_: May have custom hardware implementations with weaker precision. Additionally, subnormal values may be flushed to zero, rounding towards zero may be used, and NaN and infinity input may not be handled correctly.
• fast_: May perform internal computations using 16 bit floats. Additionally, subnormal values may be flushed to zero, and rounding towards zero may be used.

## Summary

Functions
cross Cross product of two vectors
distance Distance between two points
dot Dot product of two vectors
fast_distance Approximate distance between two points
fast_length Approximate length of a vector
fast_normalize Approximate normalized vector
length Length of a vector
native_distance Approximate distance between two points
native_length Approximate length of a vector
native_normalize Approximately normalize a vector
normalize Normalize a vector

## Functions

#### cross: Cross product of two vectors

 float3 cross(float3 left_vector, float3 right_vector); float4 cross(float4 left_vector, float4 right_vector); half3 cross(half3 left_vector, half3 right_vector); Added in API level 24 half4 cross(half4 left_vector, half4 right_vector); Added in API level 24

Computes the cross product of two vectors.

#### distance: Distance between two points

 float distance(float left_vector, float right_vector); float distance(float2 left_vector, float2 right_vector); float distance(float3 left_vector, float3 right_vector); float distance(float4 left_vector, float4 right_vector); half distance(half left_vector, half right_vector); Added in API level 24 half distance(half2 left_vector, half2 right_vector); Added in API level 24 half distance(half3 left_vector, half3 right_vector); Added in API level 24 half distance(half4 left_vector, half4 right_vector); Added in API level 24

Compute the distance between two points.

#### dot: Dot product of two vectors

 float dot(float left_vector, float right_vector); float dot(float2 left_vector, float2 right_vector); float dot(float3 left_vector, float3 right_vector); float dot(float4 left_vector, float4 right_vector); half dot(half left_vector, half right_vector); Added in API level 24 half dot(half2 left_vector, half2 right_vector); Added in API level 24 half dot(half3 left_vector, half3 right_vector); Added in API level 24 half dot(half4 left_vector, half4 right_vector); Added in API level 24

Computes the dot product of two vectors.

#### fast_distance: Approximate distance between two points

 float fast_distance(float left_vector, float right_vector); Added in API level 17 float fast_distance(float2 left_vector, float2 right_vector); Added in API level 17 float fast_distance(float3 left_vector, float3 right_vector); Added in API level 17 float fast_distance(float4 left_vector, float4 right_vector); Added in API level 17

Computes the approximate distance between two points.

The precision is what would be expected from doing the computation using 16 bit floating point values.

#### fast_length: Approximate length of a vector

 float fast_length(float v); Added in API level 17 float fast_length(float2 v); Added in API level 17 float fast_length(float3 v); Added in API level 17 float fast_length(float4 v); Added in API level 17

Computes the approximate length of a vector.

The precision is what would be expected from doing the computation using 16 bit floating point values.

#### fast_normalize: Approximate normalized vector

 float fast_normalize(float v); Added in API level 17 float2 fast_normalize(float2 v); Added in API level 17 float3 fast_normalize(float3 v); Added in API level 17 float4 fast_normalize(float4 v); Added in API level 17

Approximately normalizes a vector.

For vectors of size 1, returns -1.f for negative values, 0.f for null values, and 1.f for positive values.

The precision is what would be expected from doing the computation using 16 bit floating point values.

#### length: Length of a vector

 float length(float v); float length(float2 v); float length(float3 v); float length(float4 v); half length(half v); Added in API level 24 half length(half2 v); Added in API level 24 half length(half3 v); Added in API level 24 half length(half4 v); Added in API level 24

Computes the length of a vector.

#### native_distance: Approximate distance between two points

 float native_distance(float left_vector, float right_vector); Added in API level 21 float native_distance(float2 left_vector, float2 right_vector); Added in API level 21 float native_distance(float3 left_vector, float3 right_vector); Added in API level 21 float native_distance(float4 left_vector, float4 right_vector); Added in API level 21 half native_distance(half left_vector, half right_vector); Added in API level 24 half native_distance(half2 left_vector, half2 right_vector); Added in API level 24 half native_distance(half3 left_vector, half3 right_vector); Added in API level 24 half native_distance(half4 left_vector, half4 right_vector); Added in API level 24

Computes the approximate distance between two points.

#### native_length: Approximate length of a vector

 float native_length(float v); Added in API level 21 float native_length(float2 v); Added in API level 21 float native_length(float3 v); Added in API level 21 float native_length(float4 v); Added in API level 21 half native_length(half v); Added in API level 24 half native_length(half2 v); Added in API level 24 half native_length(half3 v); Added in API level 24 half native_length(half4 v); Added in API level 24

Compute the approximate length of a vector.

#### native_normalize: Approximately normalize a vector

 float native_normalize(float v); Added in API level 21 float2 native_normalize(float2 v); Added in API level 21 float3 native_normalize(float3 v); Added in API level 21 float4 native_normalize(float4 v); Added in API level 21 half native_normalize(half v); Added in API level 24 half2 native_normalize(half2 v); Added in API level 24 half3 native_normalize(half3 v); Added in API level 24 half4 native_normalize(half4 v); Added in API level 24

Approximately normalizes a vector.

#### normalize: Normalize a vector

 float normalize(float v); float2 normalize(float2 v); float3 normalize(float3 v); float4 normalize(float4 v); half normalize(half v); Added in API level 24 half2 normalize(half2 v); Added in API level 24 half3 normalize(half3 v); Added in API level 24 half4 normalize(half4 v); Added in API level 24

Normalize a vector.

For vectors of size 1, returns -1.f for negative values, 0.f for null values, and 1.f for positive values.

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