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Re: Re: Hold problems with FindRoot

  • To: mathgroup at
  • Subject: [mg57125] Re: [mg57073] Re: Hold problems with FindRoot
  • From: Jonas Björnerstedt <lists at>
  • Date: Mon, 16 May 2005 21:35:23 -0400 (EDT)
  • References: <> <> <>
  • Sender: owner-wri-mathgroup at

Thanks! This solved my problem. Is this an undocumented restriction in 
how FindRoot can be used, or where can I find more documentation?


Chris Chiasson wrote:

>Try changing the definitions of f and g, via a PatternTest, so that
>they are only defined for numeric arguments.
>On 5/14/05, Jonas Björnerstedt <lists at> 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
>>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.
>>>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?

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