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Bug in Convolve, version 7

  • To: mathgroup at smc.vnet.net
  • Subject: [mg98354] Bug in Convolve, version 7
  • From: dh <dh at metrohm.com>
  • Date: Wed, 8 Apr 2009 02:48:23 -0400 (EDT)


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




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