[Cbc] Possible CbcBranchDynamic.cpp BUG

[Haroldo Santos]

Dear Forrest/CBC Developers,

There is this assertion failing  in :
CbcBranchDynamic.cpp:551: virtual int
CbcBranchDynamicDecision::betterBranch(CbcBranchingObject*,
CbcBranchingObject*, double, int, double, int): Assertion `distance >= 0.0'
failed.

when I'm solving this MIP:
http://www.decom.ufop.br/haroldo/files/sprint_hidden04.lp.gz

I did some debug and discover that this fails because at a given point of
the search the distance is  -0.415667  .

Cbc0010I After 10000 nodes, 4845 on tree, 180 best solution, best possible
142.25 (1909.96 seconds)
Cbc0010I After 10100 nodes, 4849 on tree, 180 best solution, best possible
142.25 (1919.14 seconds)

Tested in Linux with CBC 2.7 stable, default compilation options and no
ThirdParty software included.

The stack trace at this point is:
#0  0x00007ffff779c5cb in CbcBranchDynamicDecision::betterBranch
(this=0xb3eee10, thisOne=
    0x12d60060, changeUp=0, numInfUp=205, changeDown=0, numInfDown=211) at
CbcBranchDynamic.cpp:555
#1  0x00007ffff784bf40 in CbcNode::chooseDynamicBranch (this=0x12d9a290,
model=0x60dcd0,
    lastNode=0x12aa7510, numberPassesLeft=4) at CbcNode.cpp:3178
#2  0x00007ffff783521c in CbcModel::chooseBranch (this=0x60dcd0,
newNode=@0x7fffffff53a0,
    numberPassesLeft=5, oldNode=0x12aa7510, cuts=...,
resolved=@0x7fffffff4d18, lastws=0x12e21f40,
    lowerBefore=0x12ac54b0, upperBefore=0x1396c2e0,
branches=@0x7fffffff4b08) at CbcModel.cpp:12642
#3  0x00007ffff783b052 in CbcModel::doOneNode (this=0x60dcd0,
baseModel=0x60dcd0,
    node=@0x7fffffff5298, newNode=@0x7fffffff53a0) at CbcModel.cpp:14299
#4  0x00007ffff78108f5 in CbcModel::branchAndBound (this=0x60dcd0,
doStatistics=0)
    at CbcModel.cpp:3797
#5  0x00007ffff7b7be8b in CbcMain1 (argc=11, argv=0x7fffffffdef8, model=...,

    callBack=0x7ffff7b67569 <dummyCallBack(CbcModel*, int)>) at
CbcSolver.cpp:5589
#6  0x00007ffff7b67bb5 in CbcMain1 (argc=11, argv=0x7fffffffdef8, model=...)
at CbcSolver.cpp:1111
#7  0x0000000000400f47 in main (argc=11, argv=0x7fffffffdef8) at
CoinSolve.cpp:336

Cheers,

Haroldo

-- 
=============================================================
Haroldo Gambini Santos
Computing Department - Universidade Federal de Ouro Preto - UFOP
email: haroldo [at ] iceb.ufop.br
home/research page: www.decom.ufop.br/haroldo/

"Computer science is no more about computers than astronomy
is about telescopes." Edsger Dijkstra
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