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Jun
13
reviewed Approve How expand Binomial[n, k] for k >= 6?
Jun
8
awarded  Nice Question
Jun
5
comment Diverging solution to coupled second order ODEs from NDSolve
@AlbertRetey Very surprising! In this case changing 1.5 to 3/2 is necessary, or WorkingPrecision -> 32 won't work at all! I used to think that though the warning NDSolve::precw will be generated, as long as a higher WorkingPrecision is set, approximate numbers in the differential equation won't influence the result. (Actually I never saw this principle failed before!)
Jun
4
reviewed Approve In there a way to derive the inverse value of CDF format MultinormalDistribution?
Jun
4
comment How to solve the differential equation with Duhamel's integral?
@MichaelE2 Er…sorry, but I just can't figure out how to calculate the n-th derivative at $t=0$ where $n>2$. $x''(0)$ can be obtained by Solve[eq /. t -> 0, x''[0]]/. x[0] -> 0 (* => x''[0] == 0.000625 *), but when it comes to D[eq, t], a $\frac{x'(0)}{\sqrt{t}}$ term involves in. One may argue that since $x'(0)=0$ so this term is (probably) zero at $t=0$, too, but when it comes to D[eq, {t, 2}], a $\frac{x''(0)}{\sqrt{t}}$ term involves in…
Jun
3
comment How to solve the differential equation with Duhamel's integral?
Oh, "Adding the dummy algebraic equation y[t] == y0[t] to the system helps with the accuracy." I missed this sentence, seems that I'm a little tired today 囧
Jun
3
awarded  Enlightened
Jun
3
awarded  Nice Answer
Jun
3
revised How to solve the differential equation with Duhamel's integral?
added 52 characters in body
Jun
3
revised How to solve the differential equation with Duhamel's integral?
added 7 characters in body
Jun
3
comment How to solve the differential equation with Duhamel's integral?
As to the accuracy part: it's possible to improve the accuracy of FunctionInterpolation, see the edit of my answer.
Jun
3
comment How to solve the differential equation with Duhamel's integral?
Very interesting. BTW the dae = y[t] == y0[t]; line isn't necessary.
Jun
3
revised How to solve the differential equation with Duhamel's integral?
A way for improving the accuracy of FunctionInterpolation is added.
Jun
1
revised How to solve the differential equation with Duhamel's integral?
added 94 characters in body
Jun
1
revised How to solve the differential equation with Duhamel's integral?
added 95 characters in body
Jun
1
answered How to solve the differential equation with Duhamel's integral?
Jun
1
revised How to solve the differential equation with Duhamel's integral?
deleted 86 characters in body; edited tags
May
29
reviewed Approve Insert points in a ContourPlot
May
26
awarded  Revival
May
26
reviewed Approve Integral not being evaluated