A lousy way of doing it is to define a binary variable y (so y = 0 or 1) and minimize y s.t. sum sum T[i,j,k] < M*y where M is some suitable large value. If the sum sum T[i,j,k] <= 0, then y is 0. Otherwise, y is 1. I'm sure that other users will have better ways of modeling this. -Marc
________________________________ From: [EMAIL PROTECTED] on behalf of Bill Sent: Wed 2/14/2007 5:47 PM To: [email protected] Subject: [Help-glpk] Glpsol IF-THEN-ELSE expression problem Hi everyone, I'm new to Glpk. I'm trying to model an optimazation problem for university timetabling. In the objective function, I need to minimize the following function, g(sum sum T[i,j,k]) g() returns 1 if (sum sum T[i,j,k]) > 0 else 0 The problem is T[i,j,k] is a variable, IF-THEN-ELSE cannot handle variables in the logical expression. Is there a way around it? Can anyone help? Thank you very much B. Song _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk ---------------------------------------------------------------------------- This e-mail and any attachments may be confidential or legally privileged. If you received this message in error or are not the intended recipient, you should destroy the e-mail message and any attachments or copies, and you are prohibited from retaining, distributing, disclosing or using any information contained herein. Please inform us of the erroneous delivery by return e-mail. Thank you for your cooperation. ----------------------------------------------------------------------------
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