Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2010

[Date Index] [Thread Index] [Author Index]

Search the Archive

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



  • Prev by Date: Re: Issuing Function Calls within a Plot command
  • Next by Date: Re: Silly question on Matrices
  • Previous by thread: Simple Q
  • Next by thread: StringForm v.s Row