Modulo fails on negative numbers

[bededict-cumberbach]

Problem:

pint returns a wrong value for modulo of a negative number.

Minimal Example:

from pint import UnitRegistry
u = UnitRegistry()

foo = -180 % 360
print(foo)
>> 180
bar = -180 * u.deg % 360
print(bar)
>> 20446.480624709635 degree

Versions:

python = 3.9.0
pint = 0.20.1

[jules-ch]

You should use :

bar = -180 * u.deg % 360 * u.deg

Or use the magnitude for your operation, pint assume dimensionless as radians so it will basically be equivalent to :

-180 degree % 360 radians

[jules-ch]

See #1344 (comment)