Hi Hans, I am very much thankful to you for helping me to solve the problem. I went through the link provided by you and tried to solve the problem. But I think there's some problem with the code. So it is not arriving at the optimal solution.In Some cases it shows optimum solution while in some it does not give optimum solution. i am writing my R code aong with this mail. Please See if i am making some mistake and help me out. Our original problem is:- Miin z = 5 * X1 + 9* X2 + 7.15 *X3 + 2 * X4 subject to X1 + X2 + X3 +X4 = 9 X1 + X4 < = 6.55 Xi>= 0; i=1,2,4. Here Ihave removed the third Quadratic constraint and made my X3 variable as a Semi Continuous variable. and define bound for it as 3.6 <= X3 <= inf.
I will write my R code for it. library(lpSolveAPI) lprec<-make.lp(0,4) set.objfn(lprec,c(5,9,7.15,0.1)) add.constraint(lprec,c(1,1,1,1),"=",9) add.constraint(lprec,c(1,0,0,1),"<=",6.55) set.semicont(lprec,columns = 3,sc=TRUE) set.bounds(lprec, lower = 3.6, upper = 10,columns =3) solve(lprec) get.objective(lprec) get.variables(lprec) Here the optimal solution is by this program is 26.28 and optimum solution is X1 = 0 , X2 = 0,X3 = 3.6, X4 = 5.4 Now I describe what is not workinig in this problem Here if u calculate manually it should allocate maximum no. of units from X4 i.e 6.55 as the value associated with X4 in objective function is minimum and remaining units should be taken from X2 as X3 should be minimum 3.6. In this case the optimum value is 22.70 and optimum solution should be X1 = 0 , X2 = 2.45 ,X3 = 0, X4 = 6.55 However By declaring the X3 as a Semicontinuous it should calculate the value of objective at X3 = 0 and X3 = 3.6 automatically and compare the optimum solutions and which ever is optimum it should give as a solution. Could U please Explain Me How Could I get the above descibed optimum solution . .X1 = 0 , X2 = 2.45 ,X3 = 0, X4 = 6.55 Please Help me as soon as possible. -- View this message in context: http://www.nabble.com/Quadratic-Constraints-tp25528480p25530692.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
