Re: Bug in LaplaceTransform?
- To: mathgroup at smc.vnet.net
- Subject: [mg97757] Re: Bug in LaplaceTransform?
- From: dh <dh at metrohm.com>
- Date: Fri, 20 Mar 2009 02:42:58 -0500 (EST)
- References: <gpsr23$mf1$1@smc.vnet.net>
Hi Wieland,
sure that's wrong. But why?
Consider:
LaplaceTransform[1, t, a] ==> 1/a
thats only correct if Re[a]>0, otherwise the transform is not defined.
Mathematica seems to assumes, that the user only asks reasonable questions.
Clearly "LaplaceTransform" is less smart than Integrate.
Daniel
Wieland Brendel wrote:
> Dear reader,
> how can it happen that Mathematica throws out -i for the Laplace
> transform of one,
>
> LaplaceTransform[1, t, I] = -i?
>
> After all the Laplace transformation (with s = I) is defined as
>
> Integrate[Exp[-I t], {t, 0, Infinity}]
>
> and should be undefined. Am I wrong or is this a bug?
>
> Thanks for an answer!
> Wieland
>