Re: Finding a function within an arbitrary expression

• To: mathgroup at smc.vnet.net
• Subject: [mg131362] Re: Finding a function within an arbitrary expression
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Mon, 1 Jul 2013 05:49:58 -0400 (EDT)
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• References: <20130630072942.2AF536A20@smc.vnet.net>

```data = {3*u[1, 0], u[0, 0]/10., 1/u[1, 0], f[u[1, 0]]};

data2 = Select[data, MemberQ[#, u[1, 0]] &]

{3*u[1, 0], 1/u[1, 0], f[u[1, 0]]}

Some other methods:

data2 = Cases[data, _?(MemberQ[#, u[1, 0]] &)] = DeleteCases[data, _?(! MemberQ[#, u[1, 0]] &)] = Select[data, ! FreeQ[#, u[1, 0]] &] = Cases[data, _?(! FreeQ[#, u[1, 0]] &)] = DeleteCases[data, _?(FreeQ[#, u[1, 0]] &)] = data[[First /@ Position[data, u[1, 0]]]]

True

Bob Hanlon

On Sun, Jun 30, 2013 at 3:29 AM, amannucci
<Anthony.J.Mannucci at jpl.nasa.gov>wrote:

> I am trying to figure out what that pattern is for the following. The
> difficulty here is that I can think textually, but not in Mathematica
> patterns.
>
> 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.
>
>
>

```

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