Speed up binomial #39891
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Speed up binomial #39891
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tscrim
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Apr 7, 2025
vbraun
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Apr 10, 2025
sagemathgh-39891: Speed up binomial As first observed in sagemath#39379, when `n` and `k` are small sage integers, `binomial(n, k)` are much slower than `n.binomial(k)`. This pull request fixes it. Now `%timeit binomial(20, 10)` is only twice slower than `%timeit 20.binomial(10)` — previously it was **30** times slower. There's also a minor patch where some code is skipped when all arguments are instances of `Element`. It is certainly a more common case for the input to be `Element` than otherwise, so we optimize for it. Another minor patch involves storing imported modules as C global variables instead of re-import every time. I think using not-overriding `_method_arguments` as an indicator of "don't call the method" (then silently catch `TypeError` and throw it away) is rather bad design, but this is not in scope here. ### 📝 Checklist <!-- Put an `x` in all the boxes that apply. --> - [x] The title is concise and informative. - [x] The description explains in detail what this PR is about. - [x] I have linked a relevant issue or discussion. - [x] I have created tests covering the changes. - [ ] I have updated the documentation and checked the documentation preview. URL: sagemath#39891 Reported by: user202729 Reviewer(s): Travis Scrimshaw
vbraun
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Apr 13, 2025
sagemathgh-39891: Speed up binomial As first observed in sagemath#39379, when `n` and `k` are small sage integers, `binomial(n, k)` are much slower than `n.binomial(k)`. This pull request fixes it. Now `%timeit binomial(20, 10)` is only twice slower than `%timeit 20.binomial(10)` — previously it was **30** times slower. There's also a minor patch where some code is skipped when all arguments are instances of `Element`. It is certainly a more common case for the input to be `Element` than otherwise, so we optimize for it. Another minor patch involves storing imported modules as C global variables instead of re-import every time. I think using not-overriding `_method_arguments` as an indicator of "don't call the method" (then silently catch `TypeError` and throw it away) is rather bad design, but this is not in scope here. ### 📝 Checklist <!-- Put an `x` in all the boxes that apply. --> - [x] The title is concise and informative. - [x] The description explains in detail what this PR is about. - [x] I have linked a relevant issue or discussion. - [x] I have created tests covering the changes. - [ ] I have updated the documentation and checked the documentation preview. URL: sagemath#39891 Reported by: user202729 Reviewer(s): Travis Scrimshaw
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As first observed in #39379, when
nandkare small sage integers,binomial(n, k)are much slower thann.binomial(k).This pull request fixes it. Now
%timeit binomial(20, 10)is only twice slower than%timeit 20.binomial(10)— previously it was 30 times slower.There's also a minor patch where some code is skipped when all arguments are instances of
Element. It is certainly a more common case for the input to beElementthan otherwise, so we optimize for it.Another minor patch involves storing imported modules as C global variables instead of re-import every time.
I think using not-overriding
_method_argumentsas an indicator of "don't call the method"(then silently catch
TypeErrorand throw it away) is rather bad design,but this is not in scope here.
📝 Checklist