Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2009

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

Search the Archive

Re: Bug in Convolve, version 7

  • To: mathgroup at smc.vnet.net
  • Subject: [mg98381] Re: Bug in Convolve, version 7
  • From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
  • Date: Wed, 8 Apr 2009 05:04:04 -0400 (EDT)
  • References: <grhhb2$j39$1@smc.vnet.net>

Hi Daniel,

Looks like a genuine bug. I found another one with Convolve:

Convolve[Sin[x], Cos[x], x, y]

Mathematica thinks it's 0, whereas the integral doesn't converge.
Interestingly, it doesn't report a result on the commuted version:

Convolve[Cos[x], Sin[x], x, y]

Cheers -- Sjoerd

On Apr 8, 8:48 am, dh <d... at metrohm.com> wrote:
> Hello,
>
> convolution is commutative, f*g == g*f.
>
> now consider the 2 calulations, where we simply exchange the first 2
>
> arguments of Convolve:
>
> f = UnitBox;
>
> Convolve[f[x1], f[x1], x1, x2]
>
> Convolve[%, f[x2], x2, x3]
>
> Convolve[%, f[x3], x3, x4]
>
> Plot[%, {x4, -2, 2}]
>
> f = UnitBox;
>
> Convolve[f[x1], f[x1], x1, x2]
>
> Convolve[f[x2], %, x2, x3]
>
> Convolve[f[x3], %, x3, x4]
>
> Plot[%, {x4, -2, 2}]
>
> wheras the first calculation is correct, the second is obviously wrong.
>
> Daniel
>
> P.S. i tried this with version 7.0.1 and Windows



  • Prev by Date: Re: Integrating package documentation with the documentation center
  • Next by Date: Table Format Problem
  • Previous by thread: Bug in Convolve, version 7
  • Next by thread: Wolfram support website documents deleted