Re: Very very basic question about Mathematica expressions

*To*: mathgroup at smc.vnet.net*Subject*: [mg111135] Re: Very very basic question about Mathematica expressions*From*: dr DanW <dmaxwarren at gmail.com>*Date*: Wed, 21 Jul 2010 07:14:35 -0400 (EDT)*References*: <i23k1j$epv$1@smc.vnet.net>

I ran into this problem yesterday. I don't know exactly why it happens, I think it has something to do with the way Manipulate localizes variables. To solve it, I use a trick I found that lets me take an expression built up of global symbols and localize the symbols. Your trivial example: s = x + h Make a function out of it. The Evaluate[] is necessary to evaluate s, which replaces it with x+h sfnc = Function[{x, h}, Evaluate[s]] Now the Manipulate[] works fine Manipulate[Plot[sfnc[x, h], {x, 0, h}], {h, 0.1, 1}] I find myself using this trick a lot. Regards, Daniel