Understanding Complex Numbers: Limits & Functions

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Homework Help Overview

The discussion revolves around the concept of limits in the context of complex functions, specifically referencing a section from Kreyszig's text on complex numbers. The original poster seeks clarification on the definition of a limit as z approaches a point z_0, particularly in relation to the behavior of the function f(z) near that point.

Discussion Character

  • Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to interpret the formal definition of a limit and seeks confirmation on their understanding of how values of f(z) behave in relation to the limit l as z approaches z_0.

Discussion Status

Some participants affirm the original poster's understanding of the limit concept, indicating that the discussion is moving towards a shared comprehension of the topic. However, there is no explicit consensus or further exploration of the implications of this understanding.

Contextual Notes

The original poster references a specific textbook section, which may imply that there are constraints or particular definitions being adhered to in this discussion.

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[SOLVED] Complex Numbers

A very happy new year to all at PF.

Homework Statement


Kreyszig, P.665 section 12.3,

A function f(z) is said to have the limit l as z approaches a point z_0 if f is defined in the neighborhood of z_0 (except perhaps at z_0 itself) and if the values of f are "close" to l for all z "close" to z_0; that is, in precise terms, for every positive real \epsilon we can find a positive real \delta such that for all z not equal to z_0 in the disk |z-z_0|<\delta, we have

|f(z)-l|<\epsilon...(2)

that is, for every z not equal to z_0 in that \delta disk, the value of f lies in the disk (2).

I think this means that if you were to plot z and f(z), for all values of z near the point z_0 (within the \delta disk), but not necessarily at z_0 itself (as the function may not exist at z_0), the value of f(z) would be very close to l (but not necessarily l, as f(z_0) may not exist) and that this value of f(z) would be inside the \epsilon disk.

Is that right?
 
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sounds good
 
Congrats, you just understood what a limit is.
 
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