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Re: Re: Solving nonlinear inequality

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91366] Re: [mg91243] Re: [mg91209] Solving nonlinear inequality
  • From: danl at wolfram.com
  • Date: Mon, 18 Aug 2008 03:37:47 -0400 (EDT)
  • References: <200808091147.HAA18525@smc.vnet.net>

> I have taken a completely different approach by using active data for
> auto-topology and using NMaximize to solve only for the leaves. This means
> small numbers of periods calculate very quickly. So after setting a 25
> period version running on our university high performance cluster I went
> to sleep at 3am.  Waking up I felt jubilant at the elegance, truth and
> beauty in my new solution.  However, I was dismayed to find the
> Mathematica
> blue  screen of death: "No more memory available. Mathematica kernel has
> shut
> down. Try quitting other applications and then retry". Of course I was the
> only person on the cluster node and all I had running was Mathematica. I
> am not sure of the memory size on our nodes so I will check this. With Red
> Hat
> linux it should be a Windows problem.
>
> Would somebody be able to help me by having a brief look at this code and
> see if I have made an error somewhere or if the code can be made both
> beautiful and run for up to 60 periods?
>
> Many thanks,
> Stuart
> [...]

(1) Get rid of all the Hold usage. If you need it, you are doing something
wrong.

(2) If you spend a bit of time debugging this, say, computing various
functions for various small values of t (e.g. inv[2]), you will quickly
learn that you have not defined \[Mu][t_]. This means there will be no end
of symbolic computation in trying to resolve various inequalities, etc.

(3) There could be other issues. For one, you might have complex values
which will cause inequalities to be unevaluated. This, too, might be
determined by computing various values (after resolving issue (2) above).

Daniel Lichtblau
Wolfram Research




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