Inverse of arbitrary functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg74497] Inverse of arbitrary functions*From*: Dave Rudolf <dave.rudolf at usask.ca>*Date*: Fri, 23 Mar 2007 19:06:35 -0500 (EST)*Organization*: University of Saskatchewan

Hey all, Is there some way to get Mathematica to find the symbolic inverse of a user-defined function? I know that I can use InverseFunction to find the inverse of simple functions, like so: InverseFunction[Log] -> Exp However, I would like to do something like f[ x_ ] = x + sin[ x + cos[ x ] ] InverseFunction[ f ] I did run across a similar newsgroup post that said to use the Solve function, like so: inverse[f_, x_] /; PolynomialQ[f, x] && Not[FreeQ[f, x]] := Module[{y}, Solve[f == y, x][[1, 1, 2]] /. y -> x] However, it doesn't seem to work as is, and I don't understand the syntax of some of the stuff. Like, what's with the -> symbol? And \; for that matter? Anyway, let me know if there is some other way to pull this off. Thanks. Dave

**Follow-Ups**:**Re: Inverse of arbitrary functions***From:*"Chris Chiasson" <chris@chiasson.name>