16 Apr

Bug reporting for CBC, NEOS, Pyomo

It was an interesting experience testing the latest SolverStudio 0.6.0 release. We discovered several independent bugs in CBC 2.8.8 on Windows which means (1) CBC often finds incorrect solutions when used with AMPL, and (2) it reports the wrong objective function value for these; thanks for Victor Zverovich from AMPL and John Forrest from COIN-OR for working with us to fix these ready for the next CBC release. We also found a bug in Pyomo’s output formatting that John Sirola is working on; we suggest for now you do not put comma’s in the values of indices. Finally, we think the output from NEOS has changed the way it is formatted; we have put in a work around while Ziliang Guo from NEOS looks into this. Who would have thought it would be such a busy week! Andrew

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