"colour.CAM16_to_XYZ" divides by zero when C = 0.

[KrisKennaway]

With 0.3.16 and python 3.9.7:

import colour.appearance.cam16 as cam16
import numpy as np
specification = cam16.CAM_Specification_CAM16(J=41.731207905126638, C=0.0, h=217.067959767393010)
XYZ_w = np.array([95.05, 100.00, 108.88])
L_A = 318.31
Y_b = 20.0
cam16.CAM16_to_XYZ(specification, XYZ_w, L_A, Y_b)
/Volumes/Stuff/apple2/dither/venv/lib/python3.9/site-packages/colour/appearance/ciecam02.py:1504: RuntimeWarning: divide by zero encountered in double_scalars
P_1 = ((50000 / 13) * N_c * N_cb * e_t) / t
array([ 19.01427392, 19.99891973, 21.76421405])

i.e. temporary_magnitude_quantity_inverse returns 0 when C = 0

I am not sure if this is just a cosmetic issue (i.e. not correctness) but it would be nice to suppress the warning if it's intentional.

[KelSolaar]

Hi @KrisKennaway,

So this is intentional, we try as much as possible to not hide anything like that so that the user can decide on the best course of action.

It is possible to granularly filter all the warnings using the colour.utilities.filter_warnings definition or the related colour.utilities.suppress_warnings context manager.

[KrisKennaway]

Thanks for the quick response. I guess my confusion is that C=0 is a perfectly valid input right? Technically working with t = inf might give the right result in that case, although I would be concerned about potential numerical instabilities from small nonzero values where t becomes arbitrarily large. I wonder if it would be better to work with 1/t instead of t here? Then I think all values should be finite.

…

On Wed, Nov 17, 2021 at 7:52 AM Thomas Mansencal ***@***.***> wrote: Hi @KrisKennaway <https://github.com/KrisKennaway>, So this is intentional, we try as much as possible to not hide anything like that so that the user can decide on the best course of action. It is possible to granularly filter all the warnings using the colour.utilities.filter_warnings <https://colour.readthedocs.io/en/develop/generated/colour.utilities.filter_warnings.html#colour.utilities.filter_warnings> definition or the related colour.utilities.suppress_warnings <https://colour.readthedocs.io/en/develop/generated/colour.utilities.filter_warnings.html#colour.utilities.suppress_warnings> context manager. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#904 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AGSNUV4HYUQBPN54IL53DK3UMNNNTANCNFSM5IGHYAGQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.