MathGroup Archive 2005

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: problem with FindRoot

  • To: mathgroup at
  • Subject: [mg54066] Re: [mg54035] problem with FindRoot
  • From: "Janos D. Pinter" <jdpinter at>
  • Date: Wed, 9 Feb 2005 09:27:49 -0500 (EST)
  • References: <>
  • Sender: owner-wri-mathgroup at

Mr/Ms qfwfq,

You can write y1<=y2<=y3<=y4 as separate constraints (notice the <= 
relations). Then use the built-in function NMInimize with the modified 
constraints, or the [commercial] packages MathOptimizer / Pro.


Janos D. Pinter, PhD, DSc
President & Research Scientist, PCS Inc.
Adjunct Professor, Dalhousie University, Halifax, NS, Canada
Research Fellow, University of Ballarat, Vic., Australia

129 Glenforest Drive, Halifax, NS, Canada B3M 1J2
Telephone: +1-(902)-443-5910
Fax: +1-(902)-431-5100; +1-(902)-443-5910
E-mail: jdpinter at
Software products:

At 06:31 AM 2/8/2005, qfwfq wrote:
>Hi all!
>I have four equations (eq1=0, ..., eq4=0) with the the four unknowns
>(y1, y2, y3, y4) in exponentials. I know the interval where the
>solutions are, and I solve this equation set by means of FindRoot by
>obtaining set of solutions. Then, I make a selection between the
>obtained results.
>However, I have a dependency between variables: y1<y2<y3<y4
>mR = Table[FindRoot[{eqn1 == 0, eqn2 == 0, eqn3 == 0, eqn4 == 0}, {y1,
>Random[Real, {a, b}]}, {y2, Random[Real, {a, b}]}, {y3, Random[Real,
>{a, b}]}, {y4, Random[Real, {a, b}]}], {24}];
>My question is
>Is there any way of include the relation between y1, ..., y4 in the
>selection of them by Random. Something like {y2, Random[Real, {y1,
>b}]}, {y3, Random[Real, {y2, b}]}, ...
>I hope I have clearly explained my problem.

  • Prev by Date: Re: bugs in Mathematica 5.1
  • Next by Date: Re: Summary: Which[] as Textbook Input, Plot[] Questions
  • Previous by thread: problem with FindRoot
  • Next by thread: Re: problem with FindRoot