math.degrees(sys.float_info.max) should throw an OverflowError exception

[franciscouzo]

BPO	28540
Nosy	@rhettinger, @mdickinson, @franciscouzo, @tonybaloney
Files	math-degrees-overflow.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/rhettinger'
closed_at = <Date 2022-04-05.18:35:17.801>
created_at = <Date 2016-10-26.21:25:41.768>
labels = ['easy', 'type-feature', '3.11']
title = 'math.degrees(sys.float_info.max) should throw an OverflowError exception'
updated_at = <Date 2022-04-05.19:14:16.911>
user = 'https://github.com/franciscouzo'

bugs.python.org fields:

activity = <Date 2022-04-05.19:14:16.911>
actor = 'mark.dickinson'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2022-04-05.18:35:17.801>
closer = 'rhettinger'
components = []
creation = <Date 2016-10-26.21:25:41.768>
creator = 'franciscouzo'
dependencies = []
files = ['45244']
hgrepos = []
issue_num = 28540
keywords = ['easy']
message_count = 8.0
messages = ['279513', '279535', '279536', '279555', '341588', '416798', '416799', '416806']
nosy_count = 4.0
nosy_names = ['rhettinger', 'mark.dickinson', 'franciscouzo', 'anthonypjshaw']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue28540'
versions = ['Python 3.11']

[franciscouzo]

Most functions in the math library raise an OverflowError when the arguments are finite but the result is not.

>>> math.exp(sys.float_info.max)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: math range error

>>> math.degrees(sys.float_info.max)
inf

[mdickinson]

I agree in principle.

On one hand, it's difficult to care too much, since math.degrees is going to be all-but-useless for inputs larger than 1e20 or so anyway (the actual angle represented is getting lost in floating-point noise by that point).

OTOH, *because* of the above, at least making the change shouldn't break any code that wasn't broken already.

[mdickinson]

Francisco: would you be interested in writing a patch?

[mdickinson]

Actually, here's a patch.

[tonybaloney]

Francisco, I recommend converting the patch into a GitHub pull request to make it easier to code review.

Mark, Raymond, please could you re-review this patch.

[rhettinger]

I'm not interested in having this move forward. AFAICT it doesn't solve any known user problems (no one has cared about this before or since this issue was opened). It slightly slows the code. And it might break some existing code that wasn't previously a need to catch an OverflowError.

Marking this as closed. If someone thinks this is really needed, feel free to reopen.

[rhettinger]

One other thought. The mental model for degrees() is just a simple scaling operation. If done in pure Python, we would get *inf* rather than an OverflowError. I don't see any value in breaking with the obvious substitution:

    >>> sys.float_info.max * (180 / pi)
    inf

[mdickinson]

FWIW, I do consider this a bug, albeit a minor one. I may find time to fix it at some point (but it's fine to leave it closed until that time comes).