https://issues.apache.org/ooo/show_bug.cgi?id=124115
Bug ID: 124115
Issue Type: DEFECT
Summary: Solver does not identify a linear model as infeasible
Product: Calc
Version: 4.0.1
Hardware: PC
OS: Windows XP
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: programming
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Created attachment 82400
--> https://issues.apache.org/ooo/attachment.cgi?id=82400&action=edit
spreadsheet that replicates the problem
The linear programming Solver is giving nonsense results for some infeasible
problems. An attached example is:
Min A2 = 10 + 0.03 * B2 + 0.5625 * C2
s.t. B2 >= 0
C2 >= 0
D2 = 1.5 * B2 - 9.81 * A2 >= 0
E2 = A2 - 4 * (A2 - 0.5 * C2) >= 0
In OpenOffice 3.3.0 or 3.2.1, the Solver recognizes this problem as infeasible.
However in 4.0.1, it is reporting success with B2 = 0, C2 = 96, D2 = -627.84,
E2 = 0. This violates the D2 constraint, so should not have been reported as a
successful solution.
I don't know when https://issues.apache.org/ooo/show_bug.cgi?id=118160 went
into a release, but my guess is this problem is related to having changed the
linear solver. As it happens I am a contributor to several COIN-OR projects,
I'm quite familiar with those solvers so if the LP as sent from Calc to CoinMP
looks correct I can help look into what's happening on the solver side.
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