MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Bug in LaplaceTransform?



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

> 




  • Prev by Date: Re: demonstrations and presentations
  • Next by Date: Re multiple points in WorldPlot
  • Previous by thread: Re: Bug in LaplaceTransform?
  • Next by thread: SparseArray[]: no warning for repeated indices