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ConstrainedMin: "assertion failed at "\[InvisibleSpace]" after perturbation steplength > 0"

• To: mathgroup at smc.vnet.net
• Subject: [mg39481] ConstrainedMin: "assertion failed at "\[InvisibleSpace]" after perturbation steplength > 0"
• From: Uri Zwick <zwick at tau.ac.il>
• Date: Wed, 19 Feb 2003 04:41:43 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

I am using Mathematica's ConstrainedMin to solve several
fairly large linear programs with rational coefficients.
(The programs involve several hundred variables and more
than a thousand constraints.)

In several cases, after hours or days of running time I
get the following message printed:

"assertion failed at "\[InvisibleSpace]" after perturbation steplength >
0"

How should I interpret this message? Are the results that
I get after the message (and indeed before it) reliable?

I tried several times to reproduce the message, starting
with a clean session, but it didn't quite work. It seems
that what I did before the call to ConstrainedMin that produced
the message is also relevant.

Did anyone encounter such problems with ConstrainMin before?

Best regards,

Uri