Dirac delta function on the complex plane?

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SUMMARY

The discussion centers on the relationship between the Dirac delta function and integrals involving complex variables, specifically examining the integral ∫ ez*(z - z0)f(z) dz*dz. It asserts that this integral is proportional to f(z0), analogous to the real integral (1/2π)∫ eiy(x - x0)f(x) dxdy = ∫ δ(x - x0)f(x) dx = f(x0). However, it is clarified that the expression ∫ ez*(z - z0)dz* cannot be equated to δ(z - z0) due to the dependency of dz* on z, which complicates the separation of variables in the integration process.

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pellman
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Supposedly,

∫ ez*(z - z0)f(z) dz*dz

is proportional to f(z0) much in the same way that

(1/2π)∫ eiy(x - x0)f(x) dxdy
= ∫ δ(x - x0)f(x) dx
= f(x0)


Is this true? Could someone help convince me of it, or point me to a text?

I would say that even if true, it would be incorrect to say that

∫ ez*(z - z0)dz* = δ(z - z0)

because the integration over dz and dz* cannot be done independently in the same way that a surface integral over dxdy in the plane can (sometimes) be separated into independent integrations over x and y. Or can it?
 
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##z^*## is only a function in ##z##, too. So what you have is ##\exp(F(z))## with ##F(z)=G(z)(z-z_0)## where ##G(z)## is the conjugation.

(I used capital letters in order to avoid confusion with your function ##f##.)
 

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