[Coin-discuss] Construct a MIP problem

[John J Forrest]

Looking OsiCpx it looks as if it sets coltype_ in OsiCpx correctly but if 
it is not a MIP in Cplex does not tell Cplex. Using writeMpsNative should 
work.





"Spencer Fung" <sklfung at cse.cuhk.edu.hk> 
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03/18/2005 12:09 PM
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John,
 
But I am using CPLEX, can it be done the same?
 
Spencer
 

From: coin-discuss-bounces at list.coin-or.org 
[mailto:coin-discuss-bounces at list.coin-or.org] On Behalf Of John J Forrest
Sent: Saturday, March 19, 2005 1:01 AM
To: Discussions about open source software for Operations Research
Subject: Re: [Coin-discuss] Construct a MIP problem
 

Spencer, 

It should work (well if you are using Clp).  I have modified the OsiClp 
unitTest to show that.  The extra code is lines 941 to 950 of 
OsiClpSolverInterfaceTest.cpp. 

If you make unitTest in COIN/Osi and run unitTest you should see two mps 
files "continuous" and "integer".  You will see that the continuous bounds 
are all UP while the integer bounds are BV. 

John Forrest 


"Spencer Fung" <sklfung at cse.cuhk.edu.hk> 
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03/17/2005 01:32 PM 


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Hi All, 
  
I am wondering how to construct a MIP problem by using constraint matrix. 
I have done the following procedure to create a MIP problem, 
  
    si->loadProblem(*matrix, NULL, col_ub, NULL, sense, rhs, NULL); 
    si->setInteger(ctype, n_cols); 
si->writeMps("problem"); 
  
However, the column type show in ?problem.mps? is still continuous. But 
after invoke the branchAndBound(), the column type is changed to integer. 
Is it possible to obtain an integer model before invoking the B&B? 
  
Thanks. 
  
Cheers, 
Spencer_______________________________________________
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