variableconstraint.java

Create a problem solver for linear programming

/*
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package ro.simplex;

import java.util.ArrayList;
import ro.utils.Fraction;

/**
 *
 * @author Doan Chien Thang
 */
public class VariableConstraint {
    private Variable leftVar;
    private ArrayList<Variable> rightVars;
    private ArrayList<Fraction> coefs;
    private Fraction value;

    public VariableConstraint(Variable leftVar, ArrayList<Variable> rightVars,
            ArrayList<Fraction> coefs, Fraction value) {
        this.leftVar = leftVar;
        this.rightVars = rightVars;
        this.coefs = coefs;
        this.value = value;
    }
    
    @Override
    public String toString() {
        String result = "";
        result += leftVar.toString() + " = " + value;
        for (int i = 0; i < rightVars.size(); i++) {
            if (coefs.get(i).isNegative()) {
                result += "  -  ";
                if (!coefs.get(i).absolute().equals(new Fraction(1)))
                     result += coefs.get(i).absolute().toString();
                result += rightVars.get(i).toString();
            }
            else if (!coefs.get(i).equals(new Fraction(0))) {
                result += "  +  ";
                if (!coefs.get(i).absolute().equals(new Fraction(1)))
                    result += coefs.get(i).absolute().toString();
                result += rightVars.get(i).toString();
            }
        }
        return result;
    }

    public Variable getLeftVar() {
        return this.leftVar;
    }

    public Fraction getValue() {
        return this.value;
    }

    public Fraction getCoef(Variable var) {
        System.out.println("@@@@@@@@@@@@ " + var);
        for (int i = 0; i < this.rightVars.size(); i++) {
            System.out.printf("%20s", this.rightVars.get(i));
            if (this.rightVars.get(i).equals(var))
                return this.coefs.get(i);
        }
        System.out.println();
        return null;
    }

    public ArrayList<Fraction> getCoefs() {
        return this.coefs;
    }

    public VariableConstraint getNewVarConstraint(Variable inVar, 
            Variable outVar, VariableConstraint varConstraint) {
        
        ArrayList<Variable> newRightVars = new ArrayList<Variable>();
        ArrayList<Fraction> newCoefs = new ArrayList<Fraction>();
        Fraction newValue;
        if (this.equals(varConstraint)) {
            Variable newLeftVar = outVar;
            int index = this.rightVars.indexOf(outVar);
            Fraction coef = this.coefs.get(index);
            for (int i = 0; i < this.rightVars.size(); i++)
                if (!this.rightVars.get(i).equals(outVar) /*&&
                !this.coefs.get(i).equals(new Fraction(0))*/) {
                    newRightVars.add(this.rightVars.get(i));
                    newCoefs.add(Fraction.divide(this.coefs.get(i), coef).getOpposite());
                }
            newValue = Fraction.divide(this.value, coef).getOpposite();
/*            for (int i = 0; i < newRightVars.size(); i++)
                newCoefs.add(Fraction.divide(
                        this.coefs.get(i), coef).getOpposite());*/
            newRightVars.add(inVar);
            newCoefs.add(Fraction.divide(new Fraction(1), coef));
            /*for (int i = 0; i < this.rightVars.size(); i++)
                if (!newRightVars.contains(this.rightVars.get(i)) &&
                !this.rightVars.get(i).equals(outVar)) {
                    newRightVars.add(this.rightVars.get(i));
                    newCoefs.add(new Fraction(0));
                }*/
           /* for (int i = 0; i < newCoefs.size(); i++)
                System.out.printf("**********%8s", newCoefs.get(i));
            System.out.println();*/
            return new VariableConstraint(newLeftVar, newRightVars,
                newCoefs, newValue);
        }
        Fraction coef;
        if (!this.getCoef(outVar).equals(new Fraction(0)))
            coef = Fraction.divide(varConstraint.getCoef(outVar),
                this.getCoef(outVar));
        else
            coef = new Fraction(0);
        if (!coef.equals(new Fraction(0))) {
            newValue = Fraction.substract(this.value,
                    Fraction.divide(varConstraint.getValue(), coef));
            for (int i = 0; i < this.rightVars.size(); i++) {
                if (!this.rightVars.get(i).equals(outVar) && !this.rightVars.get(i).equals(inVar)) {
                    //System.out.printf("===%20s", this.rightVars.get(i));
                    newRightVars.add(this.rightVars.get(i));
                    int index = varConstraint.getRightVars().indexOf(this.rightVars.get(i));
                    newCoefs.add(Fraction.substract(this.coefs.get(i),
                            Fraction.divide(varConstraint.getCoefs().get(index), coef)));
                }
            }
        } else {
            newValue = this.value;
            for (int i = 0; i < this.rightVars.size(); i++) {
                if (!this.rightVars.get(i).equals(outVar) && !this.rightVars.get(i).equals(inVar)) {
                    //System.out.printf("===%20s", this.rightVars.get(i));
                    newRightVars.add(this.rightVars.get(i));
                    int index = varConstraint.getRightVars().indexOf(this.rightVars.get(i));
                    newCoefs.add(Fraction.substract(this.coefs.get(i),
                            new Fraction(0)));
                }
            }
        }
        newRightVars.add(inVar);
        if (!coef.equals(new Fraction(0))) {
            newCoefs.add(Fraction.divide(new Fraction(1), coef));
        } else
            newCoefs.add(new Fraction(0));
        newRightVars.add(outVar);
        newCoefs.add(new Fraction(0));
        return new VariableConstraint(this.leftVar, newRightVars,
                newCoefs, newValue);
    }

    public ArrayList<Variable> getRightVars() {
        return this.rightVars;
    }
}