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How can I force Mathematica to simplify the derivative of Sign? The following

    FullSimplify[D[Sign[x], x], x > 0]

does not work. All it produces is

    Sign'[x]

(On the other hand,

    FullSimplify[D[Abs[x], x], x > 0]

goes through.)

sevec
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1 Answers1

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The Mathematica Sign function can handle complex numbers. This complicates things. If your implementation is only relevant for real numbers, it might be better to use RealSign[] because that is differentiable.

I had a similar issue and found this information in the reference pages: https://reference.wolfram.com/language/ref/Sign.html

Jasper
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