[Cbc] lp file format

[Haroldo Santos]

On Mon, Nov 13, 2017 at 10:41 AM, Bjørn Sigurd Johansen (Spider Solutions
AS) <bjorn.sigurd.johansen at spidersolutions.no> wrote:

> Thx  : )
>
>
>
> Three modelling questions:
>
>
>
>
>
> *Question 1:*  Is there any advantage in defining bounds in BOUNDS
> section rather than in SUBJECT TO section?  I.e. is one of the following
> preferred for an (integer and/or continuous) variable?
>
>
>
> SUBJECT TO
>
> I1>=0
>
> I1<=10
>
> ------------------------- alternatively -------------------------
>
> BOUNDS
>
> 0 <= I1 <= 10
>
>
>
>
> ​I think that to define in bounds is better.


>
> *Question 2:*  What is/is there any purpose of defining no bounds, i.e.
> using FREE in BOUNDS section, for integer variables?
>
>
>
> BOUNDS
>
> I1 FREE
>
​Free variables can assume positive and negative values.​


> GENERAL
>
> I1
>
> ------------------------- alternatively only -------------------------
>
> GENERAL
>
> I1
>
>
>
>
>
>
>
> *Question 3:*  Is there any difference between the following two?
>
> V1>=0
>
> V1>=+0
>
> (I have seen “+0” being used several places).
>

​When saving LPs you'll probably see -0 +0  these are all zero. When saving
the solution you'll probably see very small values (such 1e-12)  which are
zero too but appear as small values due to the limited precision arithmetic.

>
>
>
>
> Thanks in advance,
>
> Bjorn
>
>
>
>
>
>
>
> *From:* Haroldo Santos [mailto:haroldo.santos at gmail.com]
> *Sent:* mandag 13. november 2017 13:03
> *To:* Bjørn Sigurd Johansen (Spider Solutions AS) <bjorn.sigurd.johansen@
> spidersolutions.no>
> *Cc:* cbc at list.coin-or.org; cbc at coin-or.org
> *Subject:* Re: [Cbc] lp file format
>
>
>
> Hi,
>
>
>
> I think that there is no cbc specific (more precisely Osi) LP format
> documentation. The LP file format was introduced in CPLEX and I think that
> CPLEX has the official documentation.
>
>
>
>
>
>
>
> On Mon, Nov 13, 2017 at 5:54 AM, Bjørn Sigurd Johansen (Spider Solutions
> AS) <bjorn.sigurd.johansen at spidersolutions.no> wrote:
>
> Hi!
>
>
>
> Is there any description on the CBC lp file format available ?
>
>
>
> Or may the Cplex format description at http://lpsolve.sourceforge.
> net/5.0/CPLEX-format.htm be used ?
>
>
>
> Best,
>
> Bjorn
>
>
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>
>
>
>
> --
>
> =============================================================
> 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
>
>
> It has long been an axiom of mine that the little things are infinitely
> the most important.
> -- Sir Arthur Conan Doyle, "A Case of Identity"
>



-- 
=============================================================
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


It has long been an axiom of mine that the little things are infinitely
the most important.
-- Sir Arthur Conan Doyle, "A Case of Identity"
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