Simple differential equation question

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Discussion Overview

The discussion revolves around the differentiation of a complex function A(t,z) and its relation to a derived function I(t,z) defined as |A(t,z)|^2/a, where a is a constant. Participants are exploring the mathematical implications of this relationship and the appropriate differentiation techniques.

Discussion Character

  • Mathematical reasoning
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant asks if the differential of A(t,z) can be expressed in terms of I(t,z) and seeks advice on the conversion.
  • Another participant provides a formula for dI(t,z)/dz, suggesting it involves the derivative of A(t,z) and a constant factor.
  • A question is raised regarding the nature of A(t,z) and I(t,z), specifically whether A is complex and I is real.
  • A participant clarifies that A is indeed a complex quantity, leading to confusion about how to differentiate the expression for I.
  • Another participant suggests using the product rule for differentiation to address the confusion regarding the differentiation of |A(t,z)|^2.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the functions involved, particularly regarding the complex nature of A and the real nature of I. The discussion remains unresolved as participants clarify their understanding and approach to differentiation.

Contextual Notes

There are unresolved aspects regarding the assumptions about the nature of the functions and the differentiation process, particularly in the context of complex analysis.

n0_3sc
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If I have:
[tex]\frac{dA(t,z)}{dz}[/tex]

is it possible to convert this to a differential in the form:
[tex]\frac{dI(t,z)}{dz}[/tex]
given that [tex]I(t,z)=|A(t,z)|^2/a[/tex]? (Where [tex]a[/tex] is a constant).

Any advice would help, thanks.
 
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hi n0_3sc! :smile:

dI(t,z)/dz would be (2/a) A(t,z).dA(t,z)/dz
 
so there's no complex conjugate anywhere?
 
now I'm totally confused :redface:

are you saying that A is complex, but I is real? :confused:

(and in any case, I has two copies of A, and A (obviously) only has one)
 
Sorry, A is a complex quantity so |A(t,z)|^2=A(t,z)A*(t,z)

I'm confused about differentiating that.
 
product rule … A'A* + AA'* :wink:
 
thanks :)
 

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