Re: Can Plot, can't FindRoot - what gives?
- To: mathgroup at smc.vnet.net
- Subject: [mg97734] Re: Can Plot, can't FindRoot - what gives?
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Fri, 20 Mar 2009 02:38:42 -0500 (EST)
- References: <gpsrae$mm8$1@smc.vnet.net>
Aaron Fude wrote:
> Hi,
>
> Here's my code for a model problem. I do not need a solution to this
> simple problem, of course - I just need to understand why Mathematica
> is giving me an error.
>
> f[c_] := (
> s = NDSolve[{ y'[x] == c - 1, y[0] == 0}, y, {x, 0, 2*Pi}];
> (Evaluate[y[x] /. s] /. x -> 2*Pi)[[1]]
> )
> Plot[f[c], {c, 0, 10}]
> f[1]
> FindRoot[f[c] == 0, {c, 1}]
>
> I get a series of errors, the first of which is
> NDSolve::ndnum: Encountered non-numerical value for a derivative at x
> \== 0.`
>
> I'm on Win32 version 6.
>
Clear[f], then change f[c_] := ... to f[c_?NumericQ] := ...