Make D(const) error #1279
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Make D(const) error #1279
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Contributor
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Since I also stumbled about this: does it even make sense to derive with respect to a constant? Shouldn't it be considered an error? See for example this answer for an arguments why those derivatives shouldn't exist. |
Member
Author
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Yeah, it shouldn't be zero it should just be an error. We should add that error. |
This fixes an odd bug that can occur when a constant can match, like `Differential(2)(2x) == x`, when it should obviously be zero. This fixes Differential(number) == ZeroOperator which acts like a hard zero. You need ZeroOperator instead of 0 because otherwise you codegen to stuff like 0(2x) and get an error that 0 does not have a call, and `zero` the function does not do things like `zero * zero` appropriately, so constructing a simple operator that acts like a true zero is the simplest solution that enforces the safety.
Contributor
Yes. An error would probably have helped me to find the reason for the failing MWE from PR #1511 earlier. |
Contributor
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If it makes sense to you I can add that check to PR #1511. |
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I just rebased this PR to add an error for it. We could also error earlier, we might need to in some cases error in the derivative expansion. |
ChrisRackauckas
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Apr 1, 2025
ChrisRackauckas
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Apr 1, 2025
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This fixes an odd bug that can occur when a constant can match, like
Differential(2)(2x) == x, when it should obviously be zero. This fixes Differential(number) == ZeroOperator which acts like a hard zero. You need ZeroOperator instead of 0 because otherwise you codegen to stuff like 0(2x) and get an error that 0 does not have a call, andzerothe function does not do things likezero * zeroappropriately, so constructing a simple operator that acts like a true zero is the simplest solution that enforces the safety.Edit: Differential(1) => error.