# EA2Q: Convert from Euler Angles to rotation Quaternions In RSpincalc: Conversion Between Attitude Representations of DCM, Euler Angles, Quaternions, and Euler Vectors

## Description

`EA2Q` converts from Euler Angles (EA) to Quaternions (Q).

## Usage

 `1` ```EA2Q(EA, EulerOrder='zyx', ichk = FALSE, ignoreAllChk = FALSE) ```

## Arguments

 `EA` Euler Angles (EA) vector [psi, theta, phi]. `EulerOrder` Euler Order (xyx, yzy, zxz, xzx, yxy, zyz, xyz, yzx, zxy, xzy, yxz, zyx) `ichk` Logical, FALSE=disables near-singularity warnings. `ignoreAllChk` Logical, TRUE=disables all warnings and error checks (use with caution!).

## Details

Euler Angles (EA) xyz <=> x(roll) y(pitch) z(yaw) Type 1 Rotations (Tait-Bryan angles): xyz - xzy - yxz - yzx - zyx - zxy Singular if second rotation angle is -90 or 90 degrees. Type 2 Rotations (proper Euler angles): xyx - xzx - yxy - yzy - zxz - zyz Singular if second rotation angle is 0 or 180 degrees.

Euler angles [psi, theta, phi] range from -90 to 90 degrees. Tait-Bryan angles [psi, theta, phi] range from 0 to 180 degrees. Angles about Euler vectors range from 0 to 180 degrees.

## Value

Quaternions (Q) vector [q1, q2, q3, q4].

Jose Gama

## References

by John Fuller, 14 Jul 2008 SpinCalc, Function to Convert between DCM, Euler angles, Quaternions, and Euler vectors. http://www.mathworks.com/matlabcentral/fileexchange/20696-function-to-convert-between-dcm–euler-angles–quaternions–and-euler-vectors

Paolo de Leva, 01 May 2013 SpinConv, Conversion from a rotation representation type to another. http://www.mathworks.com/matlabcentral/fileexchange/41562-spinconv

`Q2EA`

## Examples

 ```1 2``` ```EAxyx <- c(-170.6607, 110.937, 136.2344) * (pi/180) EA2Q(EAxyx,'xyx') ```

### Example output

```          [,1]       [,2]       [,3]       [,4]
[1,] 0.5414699 -0.1677491 -0.7369232 -0.3682591
```

RSpincalc documentation built on May 2, 2019, 10:59 a.m.