Re: FindRoot and evaluations

*To*: mathgroup at smc.vnet.net*Subject*: [mg97005] Re: [mg96951] FindRoot and evaluations*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 1 Mar 2009 04:59:02 -0500 (EST)*Reply-to*: hanlonr at cox.net

F[x_?NumericQ] := Module[ {x0 = x}, Print[x0]; SomethingLongAndHeavy[x0]]; Bob Hanlon ---- ventutech at gmail.com wrote: ============= Let's say: F[x_]:=Module[ {x0=x}, Print[x0]; SomethingLongAndHeavy[x0] ]; now I do: FindRoot[F[x],{x,0}] and it prints: x because it first attempts to evaluate F[x] in a symbolic form. I don't want this. Because SomethingLongAndHeavy is a recursion set of relations which generates a polynomial of order... too much. What I would like to see is: 0.0001 0.0002 ... So that F[x] is treated as a blackbox, and some Newton or Bisection method is applied on this blackbox. How to do that? Thanks! Davide PS: Based on previous discussions I already tried to play with attributes HoldAll and option Evaluated, with no success.