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May
9
comment Save a C compiled function without losing the blessing of C compiler
+1. BTW it's a little surprising to me that the default Directory[] isn't included in $LibraryPath.
May
7
comment How to implement symbolic Ramanujan's summation in Mathematica?
@Anixx Yeah, the ability of Sum seems to become the new threshold. BTW the new formula using DifferenceDelta is even harder to implement… p.s. I suggest you to add these formulas to the question rather than in the comment only.
May
7
comment Speed up the auxiliary function magicSquare when $n$ is doubly-even
@ShutaoTang It's undocumented, but mentioned in a few posts here, for example this. You can have a search for more…Well, I admit I found no detailed explanation for so long. Maybe you can consider asking a separate question for this issue?
May
7
comment How to implement symbolic Ramanujan's summation in Mathematica?
@Anixx Seems to be another invalid definition: f[x_] = x; g[x_] = DifferenceDelta[f[x], x]; -NSum[ BernoulliB[Floor@n, 1]/n! Derivative[n - 1][g][0], {n, Infinity}] produces -0.5.
May
7
comment How to implement symbolic Ramanujan's summation in Mathematica?
Well, actually I really tried to solve this problem for a while on the day you raised this question, but finally be confused and worn out by the definition in the wikipedia page. There seems to be several different definitions in wiki, and none of them produces the desired result, maybe I didn't understand them correctly...
May
7
comment How to implement symbolic Ramanujan's summation in Mathematica?
@Anixx What's the definition of $\Delta[]$?
May
7
comment Speed up the auxiliary function magicSquare when $n$ is doubly-even
@ShutaoTang I've added some brief explanation, hope it helps.
May
6
comment Speed up the auxiliary function magicSquare when $n$ is doubly-even
Where's the definition of magic1? By the way Tr@Transpose@mat should be something like Tr@Reverse@mat.
May
6
comment Can we abuse notation and write equations in differential one-form?
I think you really uncovered a blind spot! Now the procedure seems to be evident: Dt[y[x]] evaluates to y'[x] Dt[x] and for any correct DE Dt[x] will be eliminated finally. But these thoughts never came to me!
May
6
comment Why does DSolve not give the expected analytical solution for a system of DAE?
I'm not an expert of DAE, but I think for a linear system it's natural to have only one solution. Can you provide a proof for your belief?
May
5
comment Problem solving a nonlinear partial differential diffusion equation
v10 manages to handle bc[[1]] and bc2[[1]]? I think they're redundant, actually they cause failures of NDSolve in v9.
May
5
comment Why does DSolve not give the expected analytical solution for a system of DAE?
Why you think your by-hand result is correct? Maple's result is the same as Mathematica's: i.stack.imgur.com/OYav3.png
May
4
comment Integral formula for the inverse Laplace transform doesn't work?
@Guesswhoitis. Long time no see, J.M. :) How about giving an answer? I'm not that familiar with Hankel contour.
May
4
comment Computing the coefficients for Gaussian integral
Is it a programming practice or you just need the Gaussian integral weights? If the latter, search GaussianQuadratureWeights in the document.
Apr
30
comment My simulation is not never finishing and it is taking so much time?
Well, "need to plot" isn't a reason for using numerical solution. The analytic solution can be used for plotting, too!
Apr
29
comment My simulation is not never finishing and it is taking so much time?
Is numerical solution necessary? Your equations can be solved analytically by DSolve.
Apr
29
comment Difficulty in getting correct Gaussian curve for diffusion of point source
Related: mathematica.stackexchange.com/a/71945/1871
Apr
29
comment Laplace transform of $\frac{1-\cos (t)}{t}$
I think you actually mean p == 2 t and the final line should be LaplaceTransform[2 Sin[t/2]^2/t, t, s], right?
Apr
28
comment Solving coupled differential equations with an eigenvalue
Seems that this hasn't been done: Hello, welcome to Mathematica.SE! I suggest the following: 1) As you receive help, try to give it too, by answering questions in your area of expertise. 2) Read the faq! 3) When you see good questions and answers, vote them up by clicking the gray triangles, because the credibility of the system is based on the reputation gained by users sharing their knowledge. Also, please remember to accept the answer, if any, that solves your problem, by clicking the checkmark sign!
Apr
28
comment Numerical solution of IVP for linear ODE with variable coefficient runs wild soon
You may want to take part in the discussion here :D, currently the transformation can be done by Assuming[0 < t < Pi/2, dChange[{y''[x] == (x^2 - 1) y[x], y[0] == 1, y[Infinity] == 0}, ArcTan@x == t, x, t, y[x]]].