[BUG]: *nan* are generated by colour.difference.delta_E_CIE1994 definition. #1206
Description
Description
Certain values passed into delta_E_CIE1994() cause an exception or nan result.
The cause looks like rounding of intermediate floating point values resulting in a square root of a negative number. For the example inputs in the reproduction section, the argument to sqrt is:
>>> delta_A**2 + delta_B**2 - delta_C**2
-2.5153490401663703e-17
A likely fix seems be to enforce a lower bound of 0 on this expression before the sqrt.
Code for Reproduction
from colour.difference import delta_E_CIE1994
v1 = [76.62311359, 0.81274256, 4.01990717]
v2 = [76.12591697, 0.82627158, 4.08682309]
delta_E_CIE1994(v1, v2, textiles=True)Exception Message
~/.local/lib/python3.10/site-packages/colour/difference/delta_e.py:220: RuntimeWarning: invalid value encountered in sqrt(delta_H = np.sqrt(delta_A**2 + delta_B**2 - delta_C**2)Environment Information
===============================================================================
* *
* Interpreter : *
* python : 3.10.6 (main, Aug 10 2022, 11:40:04) [GCC 11.3.0] *
* *
* colour-science.org : *
* colour : 0.4.1 *
* *
* Runtime : *
* imageio : 2.22.0 *
* matplotlib : 3.6.0 *
* networkx : 2.8.6 *
* numpy : 1.23.3 *
* pandas : 1.4.4 *
* scipy : 1.9.1 *
* *
===============================================================================
defaultdict(<class 'dict'>, {'Interpreter': {'python': '3.10.6 (main, Aug 10 2022, 11:40:04) [GCC 11.3.0]'}, 'colour-science.org': {'colour': '0.4.1'}, 'Runtime': {'imageio': '2.22.0', 'matplotlib': '3.6.0', 'networkx': '2.8.6', 'numpy': '1.23.3', 'pandas': '1.4.4', 'scipy': '1.9.1'}})