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Re: Separating functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg128466] Re: Separating functions
  • From: carlos at colorado.edu
  • Date: Tue, 23 Oct 2012 00:54:17 -0400 (EDT)
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On Sunday, October 21, 2012 12:12:42 AM UTC-6, car... at colorado.edu wrote:
> Hi,
> 
> 
> 
> I have a problem in identification.  In the middle of the solution of a wave propagation problem on a regular lattice using a separation-of-variables method, I get a function of the form
> 
> 
> 
>                F(x,y,t)= f(x,y) g(t)
> 
> 
> 
> in which x,y are space coordinates and t is time. Both can be very complicated and vary from problem to problem, but Mathematica' Simplify is able to factor them. Here is a fairly trivial 1D example with an F output by //InputForm:
> 
> 
> 
> 
> 
>       Bx*(-5*Em - 3*Em*=CE=BD + 2*a^2*=CF=81*=CF=89^2 - 2*a^2*=CE=BD^2*=CF=81*=CF=89^2 + 4*Em*(1 + =CE=BD)*Cos[(a*kx)/
> 
>           Sqrt[2]] - Em*(-1 + =CE=BD)*Cos[Sqrt[2]*a*kx])*(Cos[t*=CF=89] - I*Sin[t*=CF=89]))/(2*c0^2*(-1 + =CE=BD^2)*=CF=81)
> 
> 
> 
> Here g(t)=(Cos[t*=CF=89] - I*Sin[t*=CF=89])). For more complicated 2D cases, F(x,y,t) becomes a array of product functions, each taking 20-30 lines.
> 
> 
> 
> Question: is there a way to separate  f(x,y) and g(t) that does not require external intervention?
> 
> 
> 
> Thanks.

Actually this has nothing to do with the topic, but is about font mauling (see above)   Why does the new Google Groups 
convert Mathematics  greek macros like \[Nu] to meaningless character combinations?  In the old Groups 
they appeared like \[Nu] so the expression can be easily cut and pasted into a notebook.  




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