Is the derivative of a discontinuity a delta function?

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The discussion centers on the relationship between discontinuities in functions and their derivatives, specifically in the context of quantum physics as outlined in the MIT lecture notes. It establishes that if a wave function's first derivative (ψ') exhibits finite discontinuities, its second derivative (ψ'') will contain delta functions, indicating that the derivative of a discontinuity can indeed be represented as a delta function. This relationship is particularly relevant when considering step functions, where the derivative manifests as a Dirac delta function multiplied by the step amount. The concept can be rigorously defined through the framework of distributions.

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In these notes, https://ocw.mit.edu/courses/physics...-2016/lecture-notes/MIT8_04S16_LecNotes10.pdf, at the end of page 4, it is mentioned:

(3) V(x) contains delta functions. In this case ψ'' also contains delta functions: it is proportional to the product of a continuous ψ and a delta function in V. Thus ψ' has finite discontinuities.

If ψ' has finite discontinuities and ψ'' has delta functions, does that mean that the derivative of a discontinuity is a delta function?
 
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Using informal mathematics, you can think of the "derivative" of a step function being the Dirac delta function times the step amount (including sign). A function with a simple step at a point ("simple" meaning that otherwise it would be differentiable) can be thought to have a derivative with a Dirac delta term at that point. There are other kinds of discontinuities that do not work that way.

This can be made mathematically rigorous by defining "distributions".
 
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