On Sunday 11 May 2008 22:40, Dieter Kaiser wrote:
> I started to look at the code of the Maxima function $specint which
> calculate the Laplace transform. I have rearranged the code, drawn flow
> charts and added a lot of debug information to find the problems.
>
> To get an overview of the problems with the code I have taken the tabulated
> Laplace transforms from the website of EqWorld. There are 99 Examples
> tabulated. 47 examples pass the test. 53 examples don't give the tabulated
> answer. The file test_eqworld.mac includes comments to the examples which
> fails. Some answers of Maxima might be correct, but I can't show that the
> result is identical to the tabulated answer. I run this test file with the
> Maxima CVS-Version and GCL 2.6.8.
1. Unit step function is called "unit_step", not "u". Anyway, Laplace
transform code doesn't handle it.
2. Many special integral functions (Ei, Ci, Si, etc.) are not implemented in
Maxima, so you shouldn't expect them in output.
3. Maxima doesn't handle well "abs" in integration or Laplace transform.
4. You should look at "laplace" if you're expecting nouns instead of strange
Lisp symbols in output (it's a well-known bug in "specint").
--
Alexey Beshenov <al at beshenov.ru>
http://beshenov.ru/
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