[Coin-lpsolver] Clp questions

[John J Forrest]

Gleb,

First an update on your reported bug.  This arose because when you save 
and restore factorizations etc the part of the code which cleans up status 
of variables was not entered.  The only time this mattered was when a 
fixed variable had its bounds relaxed.  This is not the case for normal 
strong branching as bounds are only ever being tightened.  I have modified 
code in stable/1.5 and trunk.  This will slow down the code by a 
nanosecond or two.

> Some general Clp questions...
> 
> Is it possible to set a limit on the objective, so that simplex stops 
> after reaching a certain value?
>

If you mean when using dual then there is setDualObjectiveLimit.  If you 
mean when using primal then there is not.  What you would have to do is 
create a ClpEventHandler object (see Clp/src/unitTest.cpp) and check 
objective whenever Clp factorizes.

> What basis status is given to new variables? (needed to save the basis 
> status array  and restore after adding new vars)
> 

Columns are set to bound nearest zero.  New slacks are made basic.

John Forrest
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