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FindRoot with algebraic expressions

• To: mathgroup at smc.vnet.net
• Subject: [mg122808] FindRoot with algebraic expressions
• From: Mirko <dashiell at web.de>
• Date: Fri, 11 Nov 2011 04:54:10 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hi,

I was wondering how FindRoot works when trying to use a algebraic initial point.
I.e.:

FindRoot[h[theta]==0,{theta[m], ???}]
where h is function of theta, for example:
h[theta_]=1/(1-m)*theta[m]  
(notice that this is for a given m).

What should I use as a starting point?

If I just use 1 as a starting point, it returns a mistake. However, I could use the solution of a first step approximation, but it doesn't work as well. Here is what I mean:

t0=Solve[h1[theta]==0,theta[m]]

(where h1 is a different function, similar to h). 
Plugging t0 into ??? returns a mistake as well. This is probably due to the format? 
Although, even if I use

theta[m]/.Solve[h1[theta]==0,theta[m]]

and plugging theta[m] into ??? gives me a mistake.