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From: | William Gordon Rutherdale |
Subject: | [Help-glpk] Explanation of Instability Warning |
Date: | Sat, 17 Oct 2009 12:45:11 -0400 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Lightning/1.0pre Thunderbird/3.0b2 |
Hi. I set up a Travelling Salesman Problem model using GLPK. When I increase the number of cities, I run into this message: Warning: numerical instability (primal simplex, phase II) * 24: obj = 3.065645000e+06 infeas = 1.747e-20 (0) Could someone please tell me what this refers to and what I can do about it. For example, are there parameters I can tweak to get rid of this message? I am aware of glp_iocp but don't understand where its specific parameters can be used in the face of the issue above. Also, after that message I get a *lot* of messages like this: +555052: mip = not found yet >= 3.065645938e+06 (89009; 260251) +555716: mip = not found yet >= 3.065645938e+06 (89070; 260620) +556402: mip = not found yet >= 3.065645938e+06 (89158; 260968) Would this be related to the first problem (about numerical instability)? It seems to get stuck at this point. Any pointers would be appreciated. -Will |
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