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.