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Gottfried Lindner Mail: [EMAIL PROTECTED] Besuchen Sie unsere Seite: http://www.informatikfuchs.de/Software/GLPK/LiMath_Optimierung.htm -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Nico Moser Sent: Donnerstag, 22. Juni 2006 13:33 To: [email protected] Subject: [Help-glpk] formulation of a problem Hi, I'm in trouble with set in a problem in the glpk datastructure and I can't find answers to my questions (perhaps I looked at the wrong places). The two main problems: 1. How can I set a variable to the right hand side? If I have a constraint like this: x1+x2 <= y1 I can't set: lpx_set_row_name(lp, 3, "constraint"); lpx_set_row_bnds(lp, 3, LPX_UP, 0, y1); -> Yes, if y1 is a constant in your model and a variable in the program containing this constant value. 2. How can I set 'holes' in the matrix (if a variable is not needed in one constraint)? For instance: x1+x2 = 3 x1 <= 1 then I would think the array assignments looks like that: ia[1] = 1, ja[1] = 1, ar[1] = 1.0; ia[2] = 1, ja[2] = 2, ar[2] = 1.0; ia[3] = 2, ja[3] = 1, ar[3] = 1.0; ia[4] = 2, ja[4] = 2, ar[4] = 0; // <- it doesn't work (a similar problem: if I don't need a basic variable in the minimize or maximize funktion, can I set the the coefficient to zero? like: lpx_set_obj_coef(lp,1,0.0); ) -> Only coefficients with value <> 0 may be explicitly assigned. The others are assigned to 0 implicitly (sparse matrix storage). Thanks a lot, Nico _______________________________________________ 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
