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)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <k603ld$7lp$1@smc.vnet.net>

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.