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Re: Re: NMaximize Questions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg90972] Re: [mg90954] Re: NMaximize Questions
  • From: "Stuart Nettleton" <stuart.nettleton at optusnet.com.au>
  • Date: Fri, 1 Aug 2008 03:00:24 -0400 (EDT)
  • References: <g6rnra$7j5$1@smc.vnet.net> <200807311003.GAA11370@smc.vnet.net>

Jean-Marc,
Many thanks for your clarification of the NMaximize error message, which I  
had found quite cryptic!
I am wondering if NMaximize can be made faster for a large system of  
equations by doing some directed acyclic graph (DAC) / topological sorting  
to find the "leaves" or independent variables first. I am wondering  
whether, instead of submitting a large system of equations and variables,  
it might be faster to only submit the leaves as variables and use a  
function to topologically process the objective function.
I have looked at Reduce, but it seems to take as long or longer than  
NMaximize.
Also, NMaximize already seems to use a function like FindInstance to  
locate "true" in the identities.
I would be interested in your opinion on whether DAC preprocessing is  
likely to be of any value or if NMaximize internally uses equivalent  
techniques anyway?
Many Thanks,
Stuart

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