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visits member for 3 years, 10 months
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7h
comment 'Deriving' the Laplace Transform from the $z$ Transform: Missing a $\Delta t$
I think you need to do some kind of renormalization here. For instance, assume that the discrete signal is measuring the "energy" of the signal, so as you make the time intervals shorter, the discrete signals must go to 0.
18h
awarded  Curious
19h
comment Ricci flow and conformal classes
I am sorry I don't understand anything. Can you elaborate on it a little?
1d
asked Ricci flow and conformal classes
1d
answered Easy solution to Yamabe problem for surfaces
Aug
24
comment Bounding error when iterating a function
If you assume $f$ is Lipschitz probably you will get something.
Aug
14
comment Checking Boundary Conditions for Candidate Solutions to PDE
@Quickbeam2k1 you should make your comment an answer. As far as I am concerned, your answer is spot on, in the form of rhetorical questions.
Aug
12
reviewed Approve suggested edit on Solving $4y^4 - 4x^4 + x + y = 0$ (equation system of partial derivates)
Aug
12
answered Riemann Sum $\epsilon$ Criterion
Aug
12
answered Some kind of relation between classical heat equation and Laplace .
Aug
12
comment History of the matrix representation of complex numbers
Thanks! Of course that is Euler's formula! I should have realized that when you have such a formula it is natural to visualize it as something happening on the unit circle.
Aug
12
comment History of the matrix representation of complex numbers
From what I have read, the representation of complex numbers as points on the plane was introduced independently by Argand and Gauss around 1809. Can you please elaborate a bit on the Euler reference?
Aug
6
comment Show that the semigroup S(t) here described is a contraction semigroup
@saz: That's great! What is the counterexample?
Aug
6
revised How to prove $\tan^{-1}(n+1)-\tan^{-1}(n-1)=\tan^{-1}\big(\frac{2}{n^2}\big)$?
minor edit
Aug
4
revised Non-ellipticity of Yang-Mills equations
minor edit
Aug
4
revised Non-ellipticity of Yang-Mills equations
minor edit
Aug
2
awarded  Revival
Aug
2
comment What are the problems that you tried to find their solutions and you did not know that it is impossible?
Well, to me it does not sound those were waste of time at all.
Aug
2
revised Non-ellipticity of Yang-Mills equations
added 207 characters in body
Aug
2
comment On the definition of the Sobolev space $W^{1,p}(I)$
Yes, this is a property of convolutions. For instance, if $\varphi=0$ then all $\varphi_n=0$. The convergence of $\varphi_n'$ to $\varphi'$ is a consequence of $\varphi_n'=\rho_n*\varphi'$.