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MathGroup Archive 2007

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Re: 2D Convolution

  • To: mathgroup at smc.vnet.net
  • Subject: [mg76164] Re: 2D Convolution
  • From: Mathieu G <ellocomateo at free.fr>
  • Date: Thu, 17 May 2007 05:55:36 -0400 (EDT)
  • References: <f29389$m7p$1@smc.vnet.net> <f2bunr$jig$1@smc.vnet.net>

dh a =E9crit :
> Hi Mathieu,
>
> Note that the Gaussian and Hole covolution is symmetrical and can
>
> therefore done as a much simplier 1 dim problem. However, if you need
>
> 2dim, I would advice, due to computing time, to approximate the 2D
>
> convolution by a numerical approximation. Here is a small example:
>
> Hole[x_,y_]:=If[0.2<x^2+y^2,0,1];
>
> Gaussian[x_,y_]:=Exp[-10(x^2+y^2)];
>
> fun[x_/;NumericQ[x],y_]:=
>
>    NIntegrate[Gaussian[x-xx,y-yy] Hole[xx,yy],{xx,-2.,2.},{yy,-2.,2.}] =
 ;
>
> fun1=FunctionInterpolation[ fun[x,y]  ,{x,-1.,1.},{y,-1.,1.}]
>
> hope this helps, Daniel


Thank you for your reply!
Your comments are useful in my discoering of Mathematica.

I am not too sure why there is no NumericQ checking on y in the <fun>
function you propose? Can you tell me why please?


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