Fleet planning for Vans

    {  Exmpl10.6-1_Vanrental.mpl  }

    {  Applications of Optimization with Xpress-MP  }

    {  Chapter 10.6,  Fleeting Planning for Vans,  Size: 6x18,  Page 207 }


TITLE
    VanRental;

DATA
    NM := 6;

INDEX
    month := 1..NM;
    contr := 3..5;

DATA
    Req[month]  := (430,410,440,390,425,450);
    Cost[contr] := (1700,2200,2600);
    Ninit := 200;
    Maxlist[contr,month] := month - contr + 1;
    MinlistA[contr,month] := FORMULA(NM - contr + 1);
    Minlist[contr,month] := IF(MinlistA > month) THEN month ELSE MinlistA ENDIF;


VARIABLE
    Rent[contr,month];

MODEL

    MIN TotalCost = SUM(contr,month: Cost * Rent);

SUBJECT TO

    FulfilMonthReq[month] -> MREQ:
        IIF(month<=2, Ninit, 0) + SUM(contr,month=Maxlist..Minlist: Rent) >= Req;

END