Thanks for the reply. The trick of using an auxiliary binary variable z: 5 * z <= x <= 10 * z to make x become semi-continuous 5<=x<=10 or x=0, effectively turns a continuous problem into a mixed integer problem with all its woes. Any idea how to circumvent the execution time accompanying this? Does anyone know if semi-continuous variables is planned to be modeled in GLPK sometimes? Thanks a lot, Ariel
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Pietro Scionti Sent: Thursday, February 11, 2010 3:17 PM To: [email protected] Subject: Re: [Help-glpk] Multi-ranged column bounds Hi, you are talking about semi-continuous variables (http://lpsolve.sourceforge.net/5.5/semi-cont.htm). They are not modelled in GLPK but you can simulate them using the approach explained here: http://www.mail-archive.com/[email protected]/msg01467.html ------------------------------ Message: 4 Date: Thu, 11 Feb 2010 14:34:46 +0200 From: Ariel Daliot <[email protected]> Subject: [Help-glpk] Multi-ranged column bounds To: "[email protected]" <[email protected]> Message-ID: <b2150c16daed5547b38206d48f323ddd0a2b4e3...@srvbpi-ex.il.betterplace.local> Content-Type: text/plain; charset="us-ascii" Hello all, I am trying to solve a problem using glpk 4.42. I need the continuously valued columns to upper and lower bounds but also to be able to have a single integer value out of this bound. More specifically, I need all the columns Xi to be bounded by 6=< Xi =<16 but I also want Xi=0 to be a possible value for the variables. This is how I set the range: glp_set_col_kind(lp, Xi, GLP_CV); glp_set_col_bnds(lp, Xi, GLP_DB, 6.0, 16.0); but how can I add Xi=0 to the allowed range? Thanks in advance, Ariel -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.gnu.org/pipermail/help-glpk/attachments/20100211/43287ba8/attachment.html ------------------------------ _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk End of Help-glpk Digest, Vol 87, Issue 15 ***************************************** Archimede S.r.l. Sede Legale: Via Manzoni, 82 Ponte S. Giovanni Sede Operativa e Amministrativa: Via Settevalli, 133/v 06128 Perugia P.IVA: 01992020543 Tel. 075 515 22 11 Fax. 075 515 22 99 www.archinet.it ********************************************************************************************************************************************************************************************************************** La presente comunicazione, con le informazioni in essa contenute e ogni documento o file allegato, e' rivolta unicamente alla/e persona/e cui e' indirizzata ed alle altre da questa autorizzata/e a riceverla. Se non siete i destinatari/autorizzati siete avvisati che qualsiasi azione, copia, comunicazione, divulgazione o simili basate sul contenuto di tali informazioni e' vietata e potrebbe essere contro la legge (art. 616 C.P., D.Lgs n. 196/2003 Codice in materia di protezione dei dati personali). Se avete ricevuto questa comunicazione per errore, vi preghiamo di darne immediata notizia al mittente e di distruggere il messaggio originale e ogni file allegato senza farne copia alcuna o riprodurne in alcun modo il contenuto. This e-mail and its attachments are intended for the addressee(s) only and are confidential and/or may contain legally privileged information. If you have received this message by mistake or are not one of the addressees above, you may take no action based on it, and you may not copy or show it to anyone; please reply to this e-mail and point out the error which has occurred. ********************************************************************************************************************************************************************************************************************** _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
