Re: Finding a function within an arbitrary expression
- To: mathgroup at smc.vnet.net
 - Subject: [mg131356] Re: Finding a function within an arbitrary expression
 - From: Bill Rowe <readnews at sbcglobal.net>
 - Date: Mon, 1 Jul 2013 05:47:58 -0400 (EDT)
 - Delivered-to: l-mathgroup@mail-archive0.wolfram.com
 - Delivered-to: l-mathgroup@wolfram.com
 - Delivered-to: mathgroup-outx@smc.vnet.net
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On 6/30/13 at 3:29 AM, Anthony.J.Mannucci at jpl.nasa.gov (amannucci)
wrote:
>I am looking for a function u[1,0] within a list of expressions. The
>function might not be defined yet. For example, a list of
>expressions might be:
>{3*u[1,0], u[0,0]/10., 1/u[1,0], ...}
>I want to find all the expressions that have the function u[1,0] in
>it. There is certainly a way to do this "textually". How would one
>do this with patterns? Is it possible? Thank you.
One way:
In[53]:= DeleteCases[{3*u[1, 0], u[0, 0]/10.,
  1/u[1, 0]}, _?(FreeQ[#, u[1, 0]] &)]
Out[53]= {3*u[1, 0], 1/u[1, 0]}