Speed up multimodular algorithm in bad case #39204
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Documentation preview for this PR (built with commit ce55b7c; changes) is ready! 🎉 |
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Superseded by #39733 |
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Even with #39733, I think there is a benefit for speeding up this implementation within Sage (some people might need it for some reason). Should we reopen this? |
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Up to you, if there's some interest…? At least the change in this pull request is not overly complicated. |
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I will do the review. I should be able to get to it tomorrow. |
tscrim
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t: performance
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Apr 4, 2025
sagemathgh-39204: Speed up multimodular algorithm in bad case **Edit**: Now flint has fixed flintlib/flint#2129 , it should be better to just switch to flint entirely — according to flintlib/flint#2129 (comment) , one of the possible algorithms by flint is multimodular, which should be faster than or equal to what we're having now. If it is slower in any case, bug can be reported upstream. ------ Related to sagemath#39197. Technically the algorithm doesn't deviate from @williamstein 's original book; however the original book doesn't say *how many* additional primes to add each time. The original implementation roughly consider 3 more primes each time. This can be highly inefficient when there are more columns than rows, which makes the result's height much higher than the guess. This increases the length of `M` by roughly a factor of `1.2` each time. Worst case it makes the algorithm slower by a (hopefully small) constant factor. For the added test case, it appears to improve the performance. (Originally takes 40s, now takes <10s on my machine) ### 📝 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. ### ⌛ Dependencies <!-- List all open PRs that this PR logically depends on. For example, --> <!-- - sagemath#12345: short description why this is a dependency --> <!-- - sagemath#34567: ... --> URL: sagemath#39204 Reported by: user202729 Reviewer(s): Travis Scrimshaw
vbraun
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Apr 5, 2025
sagemathgh-39204: Speed up multimodular algorithm in bad case **Edit**: Now flint has fixed flintlib/flint#2129 , it should be better to just switch to flint entirely — according to flintlib/flint#2129 (comment) , one of the possible algorithms by flint is multimodular, which should be faster than or equal to what we're having now. If it is slower in any case, bug can be reported upstream. ------ Related to sagemath#39197. Technically the algorithm doesn't deviate from @williamstein 's original book; however the original book doesn't say *how many* additional primes to add each time. The original implementation roughly consider 3 more primes each time. This can be highly inefficient when there are more columns than rows, which makes the result's height much higher than the guess. This increases the length of `M` by roughly a factor of `1.2` each time. Worst case it makes the algorithm slower by a (hopefully small) constant factor. For the added test case, it appears to improve the performance. (Originally takes 40s, now takes <10s on my machine) ### 📝 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. ### ⌛ Dependencies <!-- List all open PRs that this PR logically depends on. For example, --> <!-- - sagemath#12345: short description why this is a dependency --> <!-- - sagemath#34567: ... --> URL: sagemath#39204 Reported by: user202729 Reviewer(s): Travis Scrimshaw
vbraun
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Apr 7, 2025
sagemathgh-39204: Speed up multimodular algorithm in bad case **Edit**: Now flint has fixed flintlib/flint#2129 , it should be better to just switch to flint entirely — according to flintlib/flint#2129 (comment) , one of the possible algorithms by flint is multimodular, which should be faster than or equal to what we're having now. If it is slower in any case, bug can be reported upstream. ------ Related to sagemath#39197. Technically the algorithm doesn't deviate from @williamstein 's original book; however the original book doesn't say *how many* additional primes to add each time. The original implementation roughly consider 3 more primes each time. This can be highly inefficient when there are more columns than rows, which makes the result's height much higher than the guess. This increases the length of `M` by roughly a factor of `1.2` each time. Worst case it makes the algorithm slower by a (hopefully small) constant factor. For the added test case, it appears to improve the performance. (Originally takes 40s, now takes <10s on my machine) ### 📝 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. ### ⌛ Dependencies <!-- List all open PRs that this PR logically depends on. For example, --> <!-- - sagemath#12345: short description why this is a dependency --> <!-- - sagemath#34567: ... --> URL: sagemath#39204 Reported by: user202729 Reviewer(s): Travis Scrimshaw
vbraun
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Apr 10, 2025
sagemathgh-39204: Speed up multimodular algorithm in bad case **Edit**: Now flint has fixed flintlib/flint#2129 , it should be better to just switch to flint entirely — according to flintlib/flint#2129 (comment) , one of the possible algorithms by flint is multimodular, which should be faster than or equal to what we're having now. If it is slower in any case, bug can be reported upstream. ------ Related to sagemath#39197. Technically the algorithm doesn't deviate from @williamstein 's original book; however the original book doesn't say *how many* additional primes to add each time. The original implementation roughly consider 3 more primes each time. This can be highly inefficient when there are more columns than rows, which makes the result's height much higher than the guess. This increases the length of `M` by roughly a factor of `1.2` each time. Worst case it makes the algorithm slower by a (hopefully small) constant factor. For the added test case, it appears to improve the performance. (Originally takes 40s, now takes <10s on my machine) ### 📝 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. ### ⌛ Dependencies <!-- List all open PRs that this PR logically depends on. For example, --> <!-- - sagemath#12345: short description why this is a dependency --> <!-- - sagemath#34567: ... --> URL: sagemath#39204 Reported by: user202729 Reviewer(s): Travis Scrimshaw
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Edit: Now flint has fixed flintlib/flint#2129 , it should be better to just switch to flint entirely — according to flintlib/flint#2129 (comment) , one of the possible algorithms by flint is multimodular, which should be faster than or equal to what we're having now. If it is slower in any case, bug can be reported upstream.
Related to #39197.
Technically the algorithm doesn't deviate from @williamstein 's original book; however the original book doesn't say how many additional primes to add each time.
The original implementation roughly consider 3 more primes each time. This can be highly inefficient when there are more columns than rows, which makes the result's height much higher than the guess.
This increases the length of
Mby roughly a factor of1.2each time. Worst case it makes the algorithm slower by a (hopefully small) constant factor.For the added test case, it appears to improve the performance. (Originally takes 40s, now takes <10s on my machine)
📝 Checklist
⌛ Dependencies