如何在Apache Commons Math SimplexSolver中設置像binary，int和double這樣的決策變量類型？

Question

如何在Apache Commons Math SimplexSolver中設置決策變量類型，如二進制，int,double？以下程序的輸出是這樣的：

332.6666666666667 
1.0 
8331.666666666668 

我想決策變量是int不double類型;如果作爲整數決策變量求解，輸出應該是333, 0, 8325。

public static void testSample() throws OptimizationException { 
    LinearObjectiveFunction f = new LinearObjectiveFunction(new double[]{25, 15}, 0); 
    Collection<LinearConstraint> constraints = new ArrayList<LinearConstraint>(); 
    constraints.add(new LinearConstraint(new double[]{5, 8}, Relationship.LEQ, 5000)); 
    constraints.add(new LinearConstraint(new double[]{1, 4}, Relationship.LEQ, 1500)); 
    constraints.add(new LinearConstraint(new double[]{3, 2}, Relationship.LEQ, 1000)); 
    constraints.add(new LinearConstraint(new double[]{1, 0}, Relationship.GEQ, 1)); 
    constraints.add(new LinearConstraint(new double[]{0, 1}, Relationship.GEQ, 1)); 

    SimplexSolver solver = new SimplexSolver(); 
    RealPointValuePair solution = solver.optimize(f, constraints, GoalType.MAXIMIZE, true); 

    System.out.println(solution.getPoint()[0]); 
    System.out.println(solution.getPoint()[1]); 
    System.out.println(solution.getValue()); 
} 

Answer 1

NumberFormat便於此：

NumberFormat nf = NumberFormat.getIntegerInstance(); 
System.out.println(nf.format(solution.getPoint()[0])); 
System.out.println(nf.format(solution.getPoint()[1])); 
System.out.println(nf.format(solution.getValue())); 

控制檯：

 
333 
1 
8,332 

附錄：這種方法假定simplex algorithm施加使用實數和結果（一個或多個）四捨五入到整數。包org.apache.commons.math.optimization.linear沒有提供其他實現。作爲替代，考慮Maxtrix<Rational>，可在JScience中獲得。