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MathGroup Archive 2002

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Memory overflow

  • To: mathgroup at smc.vnet.net
  • Subject: [mg34030] Memory overflow
  • From: dgolber at aol.com (DGolber)
  • Date: Sat, 27 Apr 2002 00:56:36 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

I'm using FindMinimum to find a curve of a certain family which best
approximates a set of points.  FindMinimum varies the parameters of the curve
to minimize the sum of squares of the distances from the points to the curve. 
Each distance from a point to the curve is itself found using FindMinimum. 
Things are complicated enough that I have Mathematica using the "Don't know the
derivatives" form of the minimizing algorithm.

There are a lot of parameters (13) and a lot of points (30), and it's slow.

But the problem is that after running about 10 minutes (350 MHz PC) the disk
starts kloncking.  I've interrupted the program, and used MaxMemoryUsed[], and
I can see the memory usage growing as the iteration proceeds.  When the memory
starts getting full, the program starts paging onto the disk.  This slows the
program down intolerably (besides which I worry about beating the disk to
death).

My question is: it's not the kind of programming where I expect the memory
usage to grow.  There's nothing recurvsive going on, that I can see.  Is there
something in FindMinimum which is recursive?  Can I turn it off?  What Tools
should I use to find out what's happening?

Thanks
Dave Golber


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