Fix incorrect multiplication #7
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thanks for finding the issue, I can merge this if you're ready. |
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Cool, thank you! I had it marked as a draft because I was investigating whether I caused a regression elsewhere but I don't think so. |
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I'm planning on submitting a handful more PRs if that's OK... If you're curious, my usecase is rewriting https://alpha.twizzle.net/explore (a tool that lets people design their own rubik's cube inspired puzzles) in Rust, using |
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Closes #6
The issue is that the early returns in
select_rootcan return early for an incorrect root. The multiplication operation leads to the polynomial 1-4x-64x²-64x³-64x³+256x⁴ which has roots at -0.25 and 0.0954.., the second of which is the correct answer. While shrinking the intervals, the lower bound landed on -0.25, which is a root, triggering the early return.This PR fixes the logic in
select_rootwhich should prevent this problem from occurring for all of the operations, not just multiplication.