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## #1 2012-10-24 21:52:56

zetafunc.
Guest

### Is this contour integration correct?

I was trying to find

, where z is complex and n is a constant.

Let z = ln(t), then dz = (1/t)dt. This transforms the integral to

Is this correct? And what would the graph of this look like?

## #2 2012-10-24 23:50:28

scientia
Member
Registered: 2009-11-13
Posts: 224

What is C?

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## #3 2012-10-24 23:58:05

zetafunc.
Guest

### Re: Is this contour integration correct?

C is some simple closed curve about 0.

## #4 2012-10-25 00:04:59

scientia
Member
Registered: 2009-11-13
Posts: 224

### Re: Is this contour integration correct?

Then shouldn't it be 0 by Cauchy's integral theorem since
is holomorphic on
?

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## #5 2012-10-25 01:08:39

zetafunc.
Guest

### Re: Is this contour integration correct?

Why is it holomorphic on C?

## #6 2012-10-25 03:42:19

scientia
Member
Registered: 2009-11-13
Posts: 224

### Re: Is this contour integration correct?

Let
so
where
and
.

Since the partial derivatives are continuous for all

and satisfy the CauchyRiemann equations
and
,
is holomorphic on the complex plane.

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## #7 2012-10-25 04:03:37

zetafunc.
Guest

### Re: Is this contour integration correct?

Thanks for that, I did not know of this method. Is that the only way to show a function like this is holomorphic on C? Would I have to do this before I evaluate any contour integral?

## #8 2012-10-25 04:10:09

zetafunc.
Guest

### Re: Is this contour integration correct?

Oh wait, I just noticed...

and since

for n ≠ 1, z ∈ Z, then every term reduces to zero, so the contour integral is zero... right?