Re: [Help-glpk] interpretation of MPS files

[Mike Steglich]

Hi Andrew and Xypron,

Thank you for your answer and the information. By knowing these information it 
is not really difficult to handle these things. I will change the (Free-)MPS 
procedures in our project (CMPL) for these cases. (... PL BOUNDS ... for an 
unbounded integer).

Cheers,
Mike
 





Am 07.03.2011 um 23:41 schrieb Andrew Makhorin:

> 
>> in glpk-4.45/src/glpmps01c you can find the following lines:
>> 
>>         else if (kind == GLP_IV)
>>            glp_set_col_bnds(csa->P, j, GLP_DB, 0.0, 1.0);
>> 
>> The GLPK default indeed seems to be an upper bound of 1.
>> 
>> lpsolve assumes an infinite upper bound, see
>> http://lpsolve.sourceforge.net/5.5/mps-format.htm
>> 
>> Same is true for Gurobi and ILOG CPLEX, see
>> http://www.gurobi.com/doc/40/refman/node580.html
>> http://www.lix.polytechnique.fr/~liberti/teaching/xct/cplex/reffileformatscplex.pdf
> 
> Xypron, looks like you have the same misreading as me a while ago :). On
> page 21 the ILOG CPLEX 10.0 manual you cited says:
> 
> "If no bounds are specified for the variables within markers [i.e. for
> integer variables - A.M.], bounds of 0 (zero) and 1 (one) are assumed.
> 
> 
>> Hence I would consider the GLPK implementation as inconsistent with
>> the defacto standard for MPS files.
>> 
> 
> 
>