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FindRoot exploration of parameter space

  • To: mathgroup at
  • Subject: [mg124603] FindRoot exploration of parameter space
  • From: NRedacted <nredacted at>
  • Date: Thu, 26 Jan 2012 03:27:30 -0500 (EST)
  • Delivered-to:

I am solving three non-linear equations in three variables (H0D,H0S and H1S) using FindRoot. In addition to the three variables of interest, there are four parameters in these equations that I would like to be able to vary. My parameters and the range in which I want to vary them are as follows: $CF \in \{0,15\}$,$CR \in \{0,8\}$,$T \in \{0,0.35\}$,$H1R \in \{40,79\}$

The problem is that my non-linear system may not have any solutions for part of this parameter range. What I basically want to ask is if there is a smart way to find out exactly what part of my parameter range admits real solutions.

I could run a FindRoot inside a loop but because of non-linearity, FindRoot is very sensitive to initial conditions so frequently error messages could be because of bad initial conditions rather than absence of a solution.

Is there a way for me to find out what parameter space works, short of plugging 10^4 combinations of parameter values by hand and playing around with the initial conditions and hoping that FindRoot gives me a solution?

Thanks a lot,

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