error messages in Mathematica 9

*To*: mathgroup at smc.vnet.net*Subject*: [mg128947] error messages in Mathematica 9*From*: Ã. Holen <o.h.holen at bio.uio.no>*Date*: Wed, 5 Dec 2012 03:12:58 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

I find that code that worked well in Mathematica 8 often produces error messages in Mathematica 9, although graphs are still produced correctly. The following code is a constructed example that illustrates the issue I'm struggling with: f[x_] := Module[{y}, y /. FindRoot[x - y, {y, 0}]]; RegionPlot[ f[x] > 0, {x, -1, 1}, {b, -1, 1}] Any suggestions about what the error is? Typical error messages are: FindRoot::nlnum: The function value {0. +Region`Private`RegionVar[1.]} is not a list of numbers with dimensions {1} at {y$897} = {0.}. >> ReplaceAll::reps: {FindRoot[Region`Private`RegionVar[1]-y$897,{y$897,0}]} is neither a list of replacement rules nor a valid dispatch table, and so cannot be used for replacing. >>