Wouter
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 Sep 2 awarded Popular Question Aug 3 comment How to numerically solve a complex equation? Would Mathematics be a better home for this question? Jul 21 comment Hodge star operator @ACuriousMind Pure math questions that arise in a physical context have recently become on-topic. Arguably, no such context has been explicitly given in this question, but I think it's clear what the physical motivation for it is. May 23 comment Algebra: What allows us to do the same thing to both sides of an equation? You currently have written $f(s)=1/x$ as an example in your fifth paragraph (if you don't count the first sentence as a separate paragraph). This should be $f(s)=s/x$. A very good answer otherwise. Mar 23 comment Explicit proof of the derivative of a matrix logarithm Hmm, in that case I'll probably have to ask another question because I'm trying to prove $\delta \det{X} = (\det{X}) \mathrm{Tr}\,(\delta M M^{-1})$. A friend asked me about this and I told him I had proved it in the context of a course on general relativity. But when I went back and looked at that proof, I noticed some of these subtleties that I seem to have brushed over when I originally wrote down the proof. Mar 23 awarded Commentator Mar 23 comment Explicit proof of the derivative of a matrix logarithm Interesting, would $\text{d}\log{X} = \text{d}X X^{-1}$ hold if $X$ were a diagonal matrix? If not, is there any other particular property that $X$ must have for this to hold? And would I be right to say that the definition in terms of a Taylor series is the fundamental one for the matrix exponential and the matrix logarithm? Mar 23 revised Explicit proof of the derivative of a matrix logarithm Qualified the kind of matrix $X$ is in my particular case Mar 23 comment Explicit proof of the derivative of a matrix logarithm @JasonZimba Thanks for the references! In my particular case $X(x)$ is a general (square) diagonalizable matrix. Mar 23 asked Explicit proof of the derivative of a matrix logarithm Nov 30 answered Relative probability Nov 22 awarded Editor Nov 22 revised Two-layer Perceptron for XOR Added idea of using -b instead of 1-b for bias Nov 21 asked Two-layer Perceptron for XOR Aug 14 comment Find value of a line integral using Stokes' theorem For future reference: mathematical physics doesn't mean "any mathematics in the context of a physics problem". And I would also suggest migrating this to Math.SE since there is no physics to be explained here and that is what Physics.SE is all about. On Math.SE, they will still ask you to show your own work but the question would be on topic there. Mar 11 awarded Supporter Feb 16 answered Question about interpretation of the divergence of a vector field Jan 29 comment Cylindrical waves That's right. On a sidenote: in this case there's no problem applying the boundary conditions because they are zero. However in general, if the BC's are e.g. $u(R,t) = f(t)$, you'd have to fourier transform those as well before applying them. (or inverse-fourier transform your solution and apply the original BC's) Jan 29 comment Cylindrical waves To see that this is a Bessel DE, try rescaling your $r$. (i.e. substitute $r' = kr$ where $k = \omega/c$) Jan 19 awarded Scholar