Function of a function problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg100114] Function of a function problem*From*: Narasimham <mathma18 at hotmail.com>*Date*: Mon, 25 May 2009 06:16:42 -0400 (EDT)

I sort of assumed that Mathematica should readily solve function of function equations like ... Equn = { f [x_] == f [ f [x] ] - 2 x } Solve[Equn, f , x] , but it does not. Is there a better some other way to code it? This is based on William Elliot's post in sci.math http://groups.google.co.in/group/sci.math/browse_thread/thread/659ea3f0d1e0efc5?hl=en# Narasimham