$ontext Illustrate user defined scaling by GAMS $offtext sets items names of variables /x1*x4/ resources names of constraints /r1*r4/ parameter objcoef(items) objective function coeficients /x1 1, x2 -500, x3 -400, x4 -5000/ rhs(resources) resource availabilities /r3 6000,r4 300/; Table amatrix(resources,items) aij matrix x1 x2 x3 x4 r1 1 -1000 -8000 r2 5 4 -50 r3 1500 2000 r4 50 45 ; variables z objective function; positive variables xvar(items) variables; equations objfun objective function avail(resources) resource limits; objfun.. z =e= sum(items,objcoef(items)*xvar(items)); avail(resources).. sum(items,amatrix(resources,items)*xvar(items)) =l= rhs(resources); option limrow=4; option limcol=0; model scalemod /all/; solve scalemod using lp maximizing z; xvar.scale("x1")=1; xvar.scale("x2")=1/1000; xvar.scale("x3")=1/1000; xvar.scale("x4")=1/50/1000; objfun.scale=1; z.scale=objfun.scale; avail.scale("r1")=1; avail.scale("r2")=1/1000; avail.scale("r3")=1; avail.scale("r4")=1/100; scalemod.scaleopt=1; solve scalemod using lp maximizing z; $ontext #user model library stuff Main topic Scaling Featured item 1 Scale Featured item 2 Scaleopt Featured item 3 Featured item 4 Description Illustrate user defined scaling by GAMS $offtext