       Re: Change multiplication operations into convolution operations

• To: mathgroup at smc.vnet.net
• Subject: [mg73609] Re: Change multiplication operations into convolution operations
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Fri, 23 Feb 2007 04:28:58 -0500 (EST)
• Organization: Uni Leipzig
• References: <erjp4f\$pt3\$1@smc.vnet.net>

```Hi,

expr = C1 F1[t] ** F2[t] + C2 F3[t] ** F4[t] ** F1[t]

try

(expr //. NonCommutativeMultiply[any___, a_[t_], b_[t_]] :>
(var = Unique[t]; NonCommutativeMultiply[any, function[Integrate[
a[# - var]*b[var], var]][t]])) /.
NonCommutativeMultiply[a_] :> a /. function -> Function

Regards
Jens

Zhao, Liang wrote:
> If I want to change the multiplication operations  into convolution
> operations in an arbitrary function such as
> C1 F1[t] F2[t] + C2 F3[t] F4[t] F1[t],
> where Fi(t) represents functions of t and Ci represents constant, into
> C1 F1[t] * F2[t] + C2 F3[t] * F4[t] * F1[t], where "*" indicate
> convolution.
>
> any good elegant way to do it? High appreciations!
>
> Liang
>
>
>

```

• Prev by Date: Re: split
• Next by Date: Roman Numerals
• Previous by thread: Re: Change multiplication operations into convolution operations
• Next by thread: Change multiplication operations into convolution operations (result & follow up question)