[Osi-tickets] [COIN-OR Open Solver Interface] #90: Changing model and re-solving can fail with the Clp backend

[COIN-OR Open Solver Interface]

#90: Changing model and re-solving can fail with the Clp backend
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 Reporter:  AndrewColes             |       Owner:  mjs
     Type:  defect                  |      Status:  new
 Priority:  major                   |   Milestone:     
Component:  OsiClp                  |     Version:     
 Keywords:  resolve objective fail  |  
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 If I load a model then do a loop:

 1) Objective to maximise column 1, solve, branch & bound
 2) Objective to maximise column 2, solve, branch & bound
 3) Objective to maximise column 3, solve, branch & bound
 ...

 then with the OsiClp backend, the code seems to fail at the first column
 for which the Objective is worse than on the previous iteration.  I can
 'fix' the problem by cloning and discarding the model for each loop, but
 this is rather inefficient.  As a comparison, with the OsiCpx backend, it
 works just fine as-is.

 Testcase attached to demonstrate this.  I'm using OSI 0.102 as checked out
 from the stable branch of the subversion repository.

 Thanks for any assistance.

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Ticket URL: <https://projects.coin-or.org/Osi/ticket/90>
COIN-OR Open Solver Interface <http://projects.coin-or.org/Osi>
An API for a variety of LP and MIP solvers (and more).