# quat2rot: Converting an unsigned unit quaternion to rotation matrix on... In Directional: A Collection of Functions for Directional Data Analysis

## Description

It forms a (3 x 3) rotation matrix on SO(3) from an unsigned unite quaternion in S^3 (the four-dimensional sphere).

## Usage

 `1` ```quat2rot(x) ```

## Arguments

 `x` An unsigned unit quaternion in S^3.

## Details

Given an unsigned unit quaternion in S^3 it forms a rotation matrix on SO(3), according to the transformation proposed by Prentice (1986).

## Value

A rotation matrix.

## Author(s)

Anamul Sajib

R implementation and documentation: Anamul Sajib <sajibstat@du.ac.bd>

## References

Prentice,M. J. (1986). Orientation statistics without parametric assumptions.Journal of the Royal Statistical Society. Series B: Methodological 48(2).

```rot2quat, rotation, Arotation rot.matrix ```

## Examples

 ```1 2 3 4``` ```x <- rnorm(4) x <- x/sqrt( sum(x^2) ) x ## an unit quaternion in R4 ## quat2rot(x) ```

### Example output

```sh: 1: wc: Permission denied
Warning messages:
1: In rgl.init(initValue, onlyNULL) : RGL: unable to open X11 display
2: 'rgl.init' failed, running with 'rgl.useNULL = TRUE'.
  0.3066565  0.4073779  0.1588596 -0.8454399
[,1]       [,2]       [,3]
[1,]  0.61761378  0.5184627 -0.5913964
[2,] -0.01876237  0.7614508  0.6479511
[3,]  0.78625772 -0.3890875  0.4800101
```

Directional documentation built on Nov. 8, 2021, 1:07 a.m.