java - 解释 model.scalar choco

Question

我很难理解model.scalar方法在 choco 库中的作用

假设我们有一个简单的有界背包问题...给定一个物品清单，其中每个物品都有重量和利润，

选择要装载到卡车上的物品，其中卡车的总重量有限制，并且

• 至少达到最低利润

• 或获得最大可能利润的地方

       int[] weights = {15, 12, 17, 20, 39, 24, 13}; //the weights of a group of item types 
       int[] profits = {4,   2,  6,  4,  9,  8,  5}; //the profit obtained from each type - must be same length as weights
       int[] stock =   {6,   8,  5,  5,  2,  4,  7}; //the maximum number of each item 
       int capacity = 300;       //maximum load weight in the truck
     int cost = 100;            //the profit threshold to be achieved (e.g. the cost of transport)
  
  
       int numTypes = weights.length;    //number of object types
  
       //calculate the max profit, for setting up the variables
       //compute as though every piece of stock could be loaded and sold
       int maxprofit = 0;
       for (int type = 0; type<numTypes; type++) {
           maxprofit += stock[type]*profits[type];
       }
  
     //Create variables
  
       IntVar[] load = new IntVar[numTypes];
       for (int type = 0; type<numTypes; type++) {
           load[type] = model.intVar("load"+type, 0,  stock[type]); //how many of each type
       }
       IntVar totalWgt = model.intVar("total wgt", 0,  capacity);    //the total weight of selected items
       IntVar totalProfit = model.intVar("profit", 0, maxprofit); //the total profit of selected items
       System.out.println("Maxprofit = " + maxprofit);
  
       //CONSTRAINTS
  
       // what is this doing?
       model.scalar(load, weights, "=", totalWgt).post();
  
       //constrain the total weight to be less than the capacity
       model.arithm(totalWgt, "<=", capacity).post();
  
       model.scalar(load, profits,  "=", totalProfit).post();
  
       //constraint the total profit to be above the cost
       model.arithm(totalProfit, ">", cost).post();
  
  
       // Solve the problem
       Solver solver = model.getSolver();
  
       // state which variable is to be maximised (or minimised)
       model.setObjective(Model.MAXIMIZE, totalProfit);
  
     while (solver.solve()) { //print the solution
           System.out.println("Solution " + solver.getSolutionCount());
   }
  

谁能解释一下标量函数在这里实际上在做什么？