Re: Re: Hold problems with FindRoot

*To*: mathgroup at smc.vnet.net*Subject*: [mg57125] Re: [mg57073] Re: Hold problems with FindRoot*From*: Jonas Björnerstedt <lists at bjornerstedt.org>*Date*: Mon, 16 May 2005 21:35:23 -0400 (EDT)*References*: <428457A1.3020501@bjornerstedt.org> <200505140858.EAA09467@smc.vnet.net> <acbec1a405051410265918dd00@mail.gmail.com>*Sender*: owner-wri-mathgroup at wolfram.com

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

**References**:**Re: Hold problems with FindRoot***From:*Jonas Björnerstedt <lists@bjornerstedt.org>