Re: Comparison of coefficients

*To*: mathgroup at smc.vnet.net*Subject*: [mg91818] Re: [mg91805] Comparison of coefficients*From*: Daniel Lichtblau <danl at wolfram.com>*Date*: Tue, 9 Sep 2008 06:55:58 -0400 (EDT)*References*: <200809080904.FAA25894@smc.vnet.net>

Kay-Michael Voit wrote: > Hello, > I'm trying to solve a PDE using a Exp ansatz. > Now I am am stuck with the equation of the form > a Exp[I k x] + b Exp[I k x] == 0 (though much more complicated) > What I would like to do is a comparison of coefficients. How can I make > Mathemetica to show me a form of the equation where I can easily read > the comparison equations? > (In the above equation > (a + b) Exp[I k x] == 0 > for example.) > > Regards > Kay-Michael Voit One way is to use Collect. I show I slightly more complicated example below. In[1]:= InputForm[Collect[a*Exp[I*k*x] + b*Exp[I*m*x] + c*Exp[I*k*x] + d*Exp[I*n*x] + e*Exp[I*m*x], Exp[_]]] Out[1]//InputForm= (a + c)*E^(I*k*x) + (b + e)*E^(I*m*x) + d*E^(I*n*x) Daniel Lichtblau WOlfram Research

**References**:**Comparison of coefficients***From:*Kay-Michael Voit <kay@voits.net>