Re: Finding a function within an arbitrary expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg131357] Re: Finding a function within an arbitrary expression*From*: "Dr. Wolfgang Hintze" <weh at snafu.de>*Date*: Mon, 1 Jul 2013 05:48:18 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net*References*: <kqomkf$p7b$1@smc.vnet.net>

Am Sonntag, 30. Juni 2013 09:27:11 UTC+2 schrieb amannucci: > 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. Hello, You could use this function which looks even for a general pattern "pat" rather than just u[1,0] f[pat_] = Complement[#1, Select[#1, FreeQ[#1, pat] & ]] & Examples x = {3*u[1, 0], u[0, 0]/10., 1/u[1, 0], u[1, 0]/2., b*Sqrt[u[1, 0]]} In[83]:= f[u[1, 0]][x] Out[83]= {1/u[1, 0], b*Sqrt[u[1, 0]], 0.5*u[1, 0], 3*u[1, 0]} In[82]:= f[u[0, 0]][x] Out[82]= {0.1*u[0, 0]} Best regards, Wolfgang