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Mathematica 8.0.1 on Mac OS X 10.7.2 does this: Quit the kernel and execute

MathieuS[MathieuCharacteristicA[  1, -(1/4)], -0.25`, 15.707963267948966`]
MathieuS[MathieuCharacteristicA[  1, -(1/4)], -0.25`, 15.707963267948966`]
(*
5.10119 10^-15
MathieuS[MathieuCharacteristicA[1, -(1/4)], -0.25, 15.708]
*)

That is, the first time it numerically evaluates the expression, while the second time it returns the unevaluated form.

Why? Or have I just spent too long staring at my screen and am doing something stupid?

Mr.Wizard
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acl
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  • Its likely you've spent too long looking at your screen, though I doubt it is the issue here. It happens on 7.0.1, also, and seems reproducible after rebooting the kernel. – rcollyer Oct 17 '11 at 19:34
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    Same result here (mma 7.0.1 on Windows 7). Looks like a bug. – Mr.Wizard Oct 17 '11 at 20:07
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    Reported as a bug. – Daniel Lichtblau Oct 17 '11 at 20:31
  • @daniel and others, thanks for the replies. Does anybody have any suggested workarounds, other than solving the ode numerically? – acl Oct 17 '11 at 20:47
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    I don't know if this is helps but as a workaround you could try running something like `MathieS[0,-0.25,0];MathieuS[MathieuCharacteristicA[1, -(1/4)], -0.25, 15.708]`. It seems that evaluating `MathieuS[a,-0.25,b]` for any other value of `a` temporarily resets `MathieuS[MathieuCharacteristicA[1, -(1/4)], -0.25, 15.708]`. – Heike Oct 17 '11 at 21:05
  • @heike thanks, I'll give that a try tomorrow. – acl Oct 17 '11 at 21:09
  • It has been reported as a bug to the developers – Anish Gupta Nov 13 '11 at 12:04

0 Answers0