Zeta function for complex argument

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SUMMARY

The discussion centers on the definition of the delta function, specifically \(\delta(x-a-ib)\), where \(a\) and \(b\) are real numbers and \(i\) represents the square root of -1. It is established that a generalized function, or distribution, does not possess a value at a specific point, but rather acts as a functional that assigns values based on integrals over a set. The standard delta function \(\delta(x)\) assigns \(f(0)\) to any function \(f\), while the shifted delta function \(\delta(x-a)\) assigns \(f(a)\). For complex arguments, \(\delta(x-a-bi)\) assigns \(f(a+bi)\) to functions of complex numbers.

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  • Familiarity with the delta function and its properties
  • Knowledge of complex numbers and their functions
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can we really give a definition of \delta (x-a-ib) a,b real and 'i' means the square root of -1

if i try it in the sense of generalized function for any x a and b i get the result oo unless b is zero
 
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zetafunction said:
can we really give a definition of \delta (x-a-ib) a,b real and 'i' means the square root of -1

if i try it in the sense of generalized function for any x a and b i get the result oo unless b is zero
No, you don't. A generalized function (distribution) does not HAVE a value at a specific point. A generalized function is a "functional" that assigns a number to every function. We can think of the functions as a subset of the generalized functions by saying that the function f(x) is the functional that to any function g(x) assigns the number \int_A f(x)g(x)dx where "A" is some given set we use to define our generalized functions.

The standard delta function, \delta(x) is the functional that assigns f(0) to every function f. The "shifted" delta function, \delta(x- a) is the functional that assigns f(a) to every function f. For a complex number, a+ bi, \delta(x-a-bi) is the functional that assigns the value f(a+bi) to every function f. Of course, for that to make sense we must be talking about functions of complex numbers, not functions of real numbers only.
 

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