- #1

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[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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- Thread starter n0_3sc
- Start date

- #1

- 243

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[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.

- #2

tiny-tim

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hi n0_3sc!

dI(t,z)/dz would be (2/a) A(t,z).dA(t,z)/dz

dI(t,z)/dz would be (2/a) A(t,z).dA(t,z)/dz

- #3

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so there's no complex conjugate anywhere?

- #4

tiny-tim

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

(and in any case, I has two copies of A, and A (obviously) only has one)

- #5

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Sorry, A is a complex quantity so |A(t,z)|^2=A(t,z)A*(t,z)

I'm confused about differentiating that.

I'm confused about differentiating that.

- #6

tiny-tim

Science Advisor

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product rule … A'A* + AA'*

- #7

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thanks :)

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