Decision Optimization

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  • 1.  Cplex error

    Posted Wed July 01, 2020 04:02 AM
    using CP;

    // Set of inputs
    int i=...; //set of origins
    int j=...; //set of destinations
    int t=...;//set of time step

    range origins=1..i;
    range destinations=1..j;
    range time=1..t;

    tuple demand {
    int demand;
    int origin;
    int destination;
    int time;
    }

    demand dm[origins][destinations][time]=...;


    float p=...;

    dvar int+ l[origins][destinations][time];
    dvar int+ u[origins][destinations][time];

    dexpr float cost1= sum(i in origins, j in destinations, t in time)(p*u[i][j][t]);

    //Objective Function
    minimize cost1;

    subject to{
    forall(i in origins, j in destinations, t in time)
    u[i][j][t]== u[i][j][t-1] + dm[i][j][t]- l[i][j][t];
    }

    The error is Operator not available for dvar int+ + <demand:int,origin:int,destination:int,time:int>.

    Data: 
    i=2;
    j=2;
    t=2;
    p = 0.1;
    dm = [ <30, 1, 1, 1>,
    <80, 2, 1, 1> ];

    What is the problem here?
    Thank you.

    ------------------------------
    Anika Tabassum
    ------------------------------


  • 2.  RE: Cplex error

    Posted Wed July 01, 2020 04:05 AM
    In
    forall(i in origins, j in destinations, t in time)
        u[i][j][t]== u[i][j][t-1] + dm[i][j][t]- l[i][j][t];
    you are trying to add integer variable u with tuple dm. You probably mean something like dm[i][j][t].demand?

    ------------------------------
    Daniel Junglas
    ------------------------------



  • 3.  RE: Cplex error

    Posted Wed July 01, 2020 12:26 PM
    Edited by Anika Tabassum Wed July 01, 2020 12:51 PM
    // Set of inputs
    int i=...; //set of origins
    int j=...; //set of destinations
    int t=...;//set of time step

    range origins=1..i;
    range destinations=1..j;
    range time=1..t;

    tuple demandType {
    int demands;
    int origins;
    int destinations;
    int time;
    }

    demandType dm=...;//Demand of vehicles


    float p=...;//Penalty cost 

    dvar int+ l[origins][destinations][time];//numbers of vehicles from origin i to destination j during t
    dvar int+ u[origins][destinations][time];//unmet demand from origin i to destination j at the end of t

    dexpr float cost1= sum(i in origins,j in destinations, t in time)(p*u[i][j][t]);

    //Objective Function
    minimize cost1;

    subject to{
    constraint1:
    forall(i in origins, j in destinations, t in time:(t-1) in time)
    u[i][j][t]== u[i][j][t-1] + dm.demands- l[i][j][t];

    constraint2:
    forall(i in origins, j in destinations, t in time)    
      l[i][j][t]<= dm.demands;

    }
    The model looks fine but the error is from the data file. 
    dm = { <19, 1,1,1>, <17, 2,1,1>, <18, 2,1,2>};
    Data item "19" unexpected for "Demand[][destinations][time]".

    ------------------------------
    Anika Tabassum
    ------------------------------

    Attachment(s)

    oplproject
    .oplproject   296 B 1 version
    mod
    partprac.mod   1011 B 1 version
    project
    .project   270 B 1 version
    dat
    demand data.dat   281 B 1 version


  • 4.  RE: Cplex error

    Posted Wed July 01, 2020 01:19 PM
    Hi

    this looks the same question as https://stackoverflow.com/questions/62664474/how-do-i-solve-a-problem-with-tuples-in-cplex/62681376#62681376

    you declared dm as

    demandType dm=...;//Demand of vehicles

    but dm is a tuple set so you d rather write

    {demandType} dm=...;//Demand of vehicles


    regards

    ------------------------------
    ALEX FLEISCHER
    ------------------------------