python / python/cpython

Decide on fate of missing C23 math.h functions

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extension-modules type-feature
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Python
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Description

Feature or enhancement

Proposal:

With https://github.com/python/cpython/issues/150534 it seems that sinpi et all will be landed in the math module. Lets discuss here remaining functions, coming with C23:

  • exp10 - The exp10 functions compute the base-10 exponential of x.
  • exp2m1 - The exp2m1 functions compute the base-2 exponential of the argument, minus 1.
  • exp10m1 - The exp10m1 functions compute the base-10 exponential of the argument, minus 1.
  • log2p1 - The log2p1 functions compute the base-2 logarithm of 1 plus the argument.
  • log10p1 - The log10p1 functions compute the base-10 logarithm of 1 plus the argument.
  • logp1 - alias of log1p, should we consider renaming?
  • rootn - The rootn functions compute the principal nth root of x.
  • rsqrt - The rsqrt functions compute the reciprocal of the nonnegative square root of the argument.

For completeness, cases that can change semantics of pow():

  • pown - The pown functions compute x raised to the nth power.
  • powr - The powr functions compute x raised to the power y as e**(y*log(x)).

References:

CC @picnixz, @rhettinger, @tim-one

I think that missing exp/log functions are good addition on same ground, as existing functions. log1p can be soft-deprecated (I don't think it worth considering deviations in naming like log1p2 and log1p10). I'm less certain about rootn (seems useful, but I would prefer rather some cmath function, that can return any k-th from n roots) and rsqrt.

Consider this as a continuation of https://github.com/python/cpython/issues/135853.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the Python math module context and the C23 references linked in the issue, then review the continuation issue #135853 and the discussion in #150534. The work is not yet implementation-ready: done means reaching a decision about which listed functions, naming changes, or semantic changes Python should adopt.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, python
Domain
api, backend
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Quiet
Clarity
Needs clarification
Newbie friendliness
28/100

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