Re: Laplace Transform bug?
- To: mathgroup at smc.vnet.net
- Subject: [mg36290] Re: Laplace Transform bug?
- From: Roland Franzius <Roland.franzius at Uos.de>
- Date: Fri, 30 Aug 2002 01:19:15 -0400 (EDT)
- Organization: Uni Osnabrueck
- References: <akkd1o$821$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Raul Martinez schrieb:
> To the Group,
>
> In[104]:=
> LaplaceTransform[D[f[t],t],t,s]
>
> Out[104]=
> -f[0] + s LaplaceTransform[f[t],t,s]
>
> In[105]:=
> LaplaceTransform[Integrate[f[t],t],t,s]
>
> Out[105]=
> LaplaceTransform[Integrate[f[t] ,t], t, s]
>
> Item 104 is correct, but item 105 is not. The correct 105 should be:
>
> -f[0]/s + LaplaceTransform[f[t],t,s]/s .
>
> If Mathematica can get 104 right, then it should also produce a correct
> 105. This looks like a bug. Any thoughts on this?
>
> (Note: Number 105 does not look like that on the notebook page. It shows
> the indefinite integral with an integral symbol followed by f[t] dt
> instead of the function Integrate[ ]. I've spelled it out because the
> e-mail won't show the symbol.)
Use the definite integral
In: LaplaceTransform[Integrate[ f[s], {s, 0, t}], t, a]
Out: LaplaceTransform[f[t], t, a]/a
--
Roland Franzius