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Bug
by manuel.munoz
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Bug: lp_solve fail to solve the following model:
max: x; x <= 0; free x; It gives 1e+30, but the optimal solution is 0. -- -------------------------------------------------- http://www.uca.es/teloydisren http://knuth.uca.es/R -------------------------------------------------- Nombre: Manuel Muñoz Márquez Departamento: Departamento de Estadística e Investigación Operativa Institución: Escuela Superior de Ingeniería de Cádiz Organización: Universidad de Cádiz Dirección: c/ Sacramento 82 Escuela Superior de Ingeniería de Cádiz 11002--Cádiz Tlf.: 956016084, 956015311 FAX: 956016050 -------------------------------------------------- Name: Manuel Munoz-Marquez Department: Statistics and Operations Research Department Institution: Escuela Superior de Ingenieria de Cadiz Organization: Universidad de Cadiz Address: c/ Sacramento 82 Escuela Superior de Ingenieria de Cadiz 11002--Cadiz, Spain Tlf.: 34956016084, 34956015313 FAX: 34956016050 e-mail: manuel.munoz@... -------------------------------------------------- |
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Re: Bug
by peter_notebaert
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That is because your model is too simple. It has no constraints. x<=0; is seen as a bound as it is written here and not as a constraint.
To force it as constraint, give it a label: max: x; R1: x <= 0; free x; You can see this also if let lp_solve you write the model: lp_solve model.lp -wlp con gives: /* Objective function */ max: +x; /* Variable bounds */ x >= -Inf; With the label it gives: /* Objective function */ max: +x; /* Constraints */ R1: +x <= 0; /* Variable bounds */ x >= -Inf; Peter --- In lp_solve@..., Manuel Muñoz Márquez <manuel.munoz@...> wrote: > > Bug: lp_solve fail to solve the following model: > > max: x; > x <= 0; > free x; > > It gives 1e+30, but the optimal solution is 0. > > -- > > -------------------------------------------------- > http://www.uca.es/teloydisren > http://knuth.uca.es/R > -------------------------------------------------- > Nombre: Manuel Muñoz Márquez > Departamento: Departamento de EstadÃstica e Investigación > Operativa > Institución: Escuela Superior de IngenierÃa de Cádiz > Organización: Universidad de Cádiz > Dirección: c/ Sacramento 82 > Escuela Superior de IngenierÃa de Cádiz > 11002--Cádiz > Tlf.: 956016084, 956015311 > FAX: 956016050 > -------------------------------------------------- > Name: Manuel Munoz-Marquez > Department: Statistics and Operations Research Department > Institution: Escuela Superior de Ingenieria de Cadiz > Organization: Universidad de Cadiz > Address: c/ Sacramento 82 > Escuela Superior de Ingenieria de Cadiz > 11002--Cadiz, Spain > > Tlf.: 34956016084, 34956015313 > FAX: 34956016050 > > e-mail: manuel.munoz@... > -------------------------------------------------- > |
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Re: Re: Bug
by manuel.munoz
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El mié, 04-11-2009 a las 10:59 +0000, peter_notebaert escribió:
> > That is because your model is too simple. It has no constraints. x<=0; > is seen as a bound as it is written here and not as a constraint. > > To force it as constraint, give it a label: > > max: x; > R1: x <= 0; > free x; > I can see. But why I can write, by example, x+y <10 without a label but not x <= 0? Thank you, Peter. -- -------------------------------------------------- http://www.uca.es/teloydisren http://knuth.uca.es/R -------------------------------------------------- Nombre: Manuel Muñoz Márquez Departamento: Departamento de Estadística e Investigación Operativa Institución: Escuela Superior de Ingeniería de Cádiz Organización: Universidad de Cádiz Dirección: c/ Sacramento 82 Escuela Superior de Ingeniería de Cádiz 11002--Cádiz Tlf.: 956016084, 956015311 FAX: 956016050 -------------------------------------------------- Name: Manuel Munoz-Marquez Department: Statistics and Operations Research Department Institution: Escuela Superior de Ingenieria de Cadiz Organization: Universidad de Cadiz Address: c/ Sacramento 82 Escuela Superior de Ingenieria de Cadiz 11002--Cadiz, Spain Tlf.: 34956016084, 34956015313 FAX: 34956016050 e-mail: manuel.munoz@... -------------------------------------------------- |
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Re: Re: Bug
by peter_notebaert
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Look in the reference guide in the explanation of the lp-format (
http://lpsolve.sourceforge.net/5.5/lp-format.htm) Peter 2009/11/4 Manuel Muñoz Márquez <manuel.munoz@...> > > > El mié, 04-11-2009 a las 10:59 +0000, peter_notebaert escribió: > > > > > That is because your model is too simple. It has no constraints. x<=0; > > is seen as a bound as it is written here and not as a constraint. > > > > To force it as constraint, give it a label: > > > > max: x; > > R1: x <= 0; > > free x; > > > > I can see. But why I can write, by example, x+y <10 without a label but > not x <= 0? > > Thank you, Peter. > > > -- > > -------------------------------------------------- > http://www.uca.es/teloydisren > http://knuth.uca.es/R > -------------------------------------------------- > Nombre: Manuel Muñoz Márquez > Departamento: Departamento de Estadística e Investigación > Operativa > Institución: Escuela Superior de Ingeniería de Cádiz > Organización: Universidad de Cádiz > Dirección: c/ Sacramento 82 > Escuela Superior de Ingeniería de Cádiz > 11002--Cádiz > Tlf.: 956016084, 956015311 > FAX: 956016050 > -------------------------------------------------- > Name: Manuel Munoz-Marquez > Department: Statistics and Operations Research Department > Institution: Escuela Superior de Ingenieria de Cadiz > Organization: Universidad de Cadiz > Address: c/ Sacramento 82 > Escuela Superior de Ingenieria de Cadiz > 11002--Cadiz, Spain > > Tlf.: 34956016084, 34956015313 > FAX: 34956016050 > > e-mail: manuel.munoz@... <manuel.munoz%40uca.es> > -------------------------------------------------- > > > |
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