Re: Re: Hold problems with FindRoot

• To: mathgroup at smc.vnet.net
• Subject: [mg57091] Re: [mg57073] Re: Hold problems with FindRoot
• From: Chris Chiasson <chris.chiasson at gmail.com>
• Date: Sun, 15 May 2005 03:03:44 -0400 (EDT)
• References: <428457A1.3020501@bjornerstedt.org> <200505140858.EAA09467@smc.vnet.net>
• Reply-to: Chris Chiasson <chris.chiasson at gmail.com>
• Sender: owner-wri-mathgroup at wolfram.com

Try changing the definitions of f and g, via a PatternTest, so that
they are only defined for numeric arguments.

f[x_?NumericQ,y_?NumericQ]=blahblah1
g[x_?NumericQ,y_?NumericQ]=blahblah2

On 5/14/05, Jonas Björnerstedt <lists at bjornerstedt.org> wrote:
> Hello again,
>
> There was a small mistake in my previous posting. It should have said:
>
> FindRoot[Evaluate[{f[x,y]==0, g[x,y]==0}],{{x,1},{y,1}}]
>
> where f and g are functions that work correctly. Trying to solve one
> equation for two unknowns would cause other problems than I am currently
> having.
>
> Jonas.
>
> Jonas Björnerstedt wrote:
>
> > Hello all,
> >
> > I have problems getting FindRoot to evaluate the equations it
> > evaluates, despite using Evaluate on the equations. I have a rather
> > complex function f[x,y] that works correctly with individual values x
> > and y. Evaluating the following expression does not work however.
> >
> > FindRoot[Evaluate[f[x,y]==0],{{x,1},{y,1}}]
> >
> > When evaluating, I get similar errors as when I evaluate f without
> > inserting values for x and y. I can also do a Plot3D on f without
> > using Evaluate.
> >
> > Does anybody have an idea what the problem is?
> >
> > Jonas
> >
>
>

--
Chris Chiasson
http://chrischiasson.com/
1 (810) 265-3161

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