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Jan
3
accepted Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
Jan
3
comment Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
Oh! So then if in your first equation I replace $i$ by $l$ and also replace both $p$ and $q$ by $l$ I get the expression with the $l$ from the the defintion of $g^{ij}$ right? I can't thank you enough! XD
Jan
3
comment Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
Also thank you so much for your help!!
Jan
3
comment Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
So the second term I managed to set equal to<br> $-\sum \frac{\partial y}{\partial x^i} \frac{\partial y}{\partial x^i} \Gamma ^j \frac{\partial f}{\partial y^k}$<br> But over which indices do I do the summation and which y components do derive in the $\frac{\partial y}{\partial x^i}$ expressions?
Jan
3
revised Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
edited body
Jan
3
comment Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
@WillieWong Sorry again! You're right of course XD However now I'm completely lost as I don't really understand how to apply $\widetilde{\nabla}$ to $f$
Jan
3
revised Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
edited body
Jan
3
comment Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
@WillieWong oh, sorry about that, forgot a pair of brackets, other than that it's what I've got in my notes. I'm afraid I still don't quite see the connection between the two expressions, especially because the right hand side seems to sum over so many different indices.
Jan
3
revised Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
added 2 characters in body
Jan
3
awarded  Scholar
Jan
3
awarded  Supporter
Jan
3
accepted Fourier transform of $ \frac{\sinh(kx)}{\sinh(x)}$
Jan
3
asked Laplacian in $\mathbb{R}^n$ expressed with Christoffel symbols
Jan
3
comment Fourier transform of $ \frac{\sinh(kx)}{\sinh(x)}$
Thank you! Finally managed to write a commentated solution!
Jan
3
comment Fourier transform of $ \frac{\sinh(kx)}{\sinh(x)}$
@rlgordonma Oh, right forgot that the contour should be in the lower half-plane. Is the argument that because the zeros of sinh(x) don't have a limit they're countable and that's why I can use the theorem?
Jan
3
comment Fourier transform of $ \frac{\sinh(kx)}{\sinh(x)}$
@rlgordonma That's the way we learned it (as far as I know) and also on wikipedia they state: "Suppose U is a simply connected open subset of the complex plane, and a1,...,an are finitely many points of U and f is a function which is defined and holomorphic on U \ {a1,...,an}." link I took that to mean, that the theorem only applied to a finite amount of residues, have I misunderstood this?
Jan
3
comment Fourier transform of $ \frac{\sinh(kx)}{\sinh(x)}$
@DavideGiraudo SORRY! really bad typo :S it is still supposed to be sinh
Jan
3
awarded  Editor
Jan
3
revised Fourier transform of $ \frac{\sinh(kx)}{\sinh(x)}$
added 2 characters in body
Jan
3
awarded  Student