Re: Simple Q
- To: mathgroup at smc.vnet.net
- Subject: [mg111540] Re: Simple Q
- From: Peter Pein <petsie at dordos.net>
- Date: Wed, 4 Aug 2010 07:33:47 -0400 (EDT)
- References: <i38rk4$dao$1@smc.vnet.net>
Am Tue, 3 Aug 2010 10:39:00 +0000 (UTC)
schrieb KFUPM <hussain.alqahtani at gmail.com>:
> Dear All
>
> I have the expression
>
> E^(I km Subscript[X, 0] +
> I \[Lambda] Subscript[X,
> 0]) (-(1/2) I kz^2 Am[Subscript[X, 1]] Coss[(m \[Pi] y)/B] -
> 1/2 I km \[Lambda] Am[Subscript[X, 1]] Coss[(m \[Pi] y)/B]) +
> E^(I km Subscript[X, 0] -
> I \[Lambda] Subscript[X,
> 0]) (1/2 I kz^2 Am[Subscript[X, 1]] Coss[(m \[Pi] y)/B] -
> 1/2 I km \[Lambda] Am[Subscript[X, 1]] Coss[(m \[Pi] y)/B]) +
> E^(I kn Subscript[X, 0] +
> I \[Lambda] Subscript[X,
> 0]) (-(1/2) I kz^2 An[Subscript[X, 1]] Coss[(n \[Pi] y)/B] -
> 1/2 I kn \[Lambda] An[Subscript[X, 1]] Coss[(n \[Pi] y)/B]) +
> E^(I kn Subscript[X, 0] -
> I \[Lambda] Subscript[X,
> 0]) (1/2 I kz^2 An[Subscript[X, 1]] Coss[(n \[Pi] y)/B] -
> 1/2 I kn \[Lambda] An[Subscript[X, 1]] Coss[(n \[Pi] y)/B]) +
> E^(I km Subscript[X, 0]) Coss[(m \[Pi] y)/B]
> \!\(\*SuperscriptBox["Bm", "\[Prime]",
> MultilineFunction->None]\)[0] +
> E^(I kn Subscript[X, 0]) Coss[(n \[Pi] y)/B]
> \!\(\*SuperscriptBox["Bn", "\[Prime]",
> MultilineFunction->None]\)[0]
>
> I want to extract terms that contain E^(I km Subscript[X, 0]) only and
> I need this to be done automatically. I appreciate any help in this
> regard.
>
>
> HMQ
>
Hi,
say the variable "expr" holds your expression; then
Cases[ExpandAll[expr /. E^(s_Plus) :> Times[Exp /@ s]],
c_.*E^(I*km*Subscript[X, 0])]
gives you a list:
{ E^(I*km*Subscript[X,0])*Coss[(m*Pi*y)/B],
(-I)*E^(I*km*Subscript[X, 0])*km*\[Lambda]*
Am[Subscript[X, 1]]*Coss[(m*Pi*y)/B]
}
Peter