|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|
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.
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