spacepy.coordinates.quaternionToMatrix

spacepy.coordinates.quaternionToMatrix(Qin, scalarPos='last', normalize=True)[source]

Given an input quaternion, return the equivalent rotation matrix.

The output has one more axis than the input (the last axis) and the shape is otherwise unchanged, allowing multi-dimensional quaternion input.

Parameters:
Qinarray_like

input quaternion or array of quaternions, must be normalized.

Returns:
outarray_like

Rotation matrix

Other Parameters:
scalarPosstr

Location of the scalar component of the input quaternion, either ‘last’ (default) or ‘first’.

normalizeTrue

Normalize input quaternions before conversion (default). If False, raises error for non-normalized.

Raises:
NotImplementedError

for invalid values of scalarPos.

ValueError

for inputs which are not valid normalized quaternions or arrays thereof: if the size doesn’t end in (4), if the quaternion is not normalized and normalize is False.

See also

quaternionFromMatrix

Notes

New in version 0.2.2.

Implementation of the Euler–Rodrigues formula.

Examples

>>> import spacepy.coordinates
>>> spacepy.coordinates.quaternionToMatrix([0.5, 0.5, 0.5, 0.5])
array([[ 0.,  0.,  1.],
       [ 1.,  0.,  0.],
       [ 0.,  1.,  0.]])