[Sinkleberg]

Description

Adds xt::sinc(e), which evaluates sin(pi*x)/(pi*x) element by element and returns one at zero. It works lazily with arrays, views and composed expressions. This addresses the sinc item in #1608.

All 1,250 tests in the default suite passed. The sinc tests also passed with xsimd enabled, and Doxygen rendered the API entry. The float build emitted a conversion warning at the existing pi constant. Full Sphinx and pre-commit checks were not run.

Checklist

• The title and commit message are descriptive.
• The change is a single commit.
• Tests cover the new function.
• The API is documented.

[codspeed]

Merging this PR will not alter performance

1 warning

⚠️ Unable to measure the execution of 1 benchmark

This benchmark measured no execution time, so its result is not comparable and counts as unchanged. This usually happens when the compiler removes the code under test.

Prevent compiler optimizations

See affected benchmarks

✅ 255 untouched benchmarks

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_{Comparing Sinkleberg:codex/normalized-sinc (8b9fdfe) with master (75abad5)}