java - 负符号数有问题

Question

我正在用 Java 做一个简单的测试，(我是初学者)我试图制作一个程序来计算二阶方程的判别式并显示结果，但是当我改变 nom1 的符号时和 nom2，该程序不显示任何结果，我已经进行了一些测试，我确定问题就在那里，但我不知道如何解决。欢迎任何帮助。

这是我的代码:

public class test {
    public static void main(String[] args) {

        double a = 2;
        double b = 5;
        double c = 3;

        double delta = b*b - 4 * a * c;

        double den = 2 * a;

        if(delta == 0){
            double nom = b;
            double pgcd = pgcd(nom, den);
            double x0nom = nom/pgcd;
            double x0den = den/pgcd;
            System.out.println("x0 = "+String.valueOf(x0nom)+" / "+String.valueOf(x0den));
        }else if(delta > 0){
            // x1:
            double nom1 = -b + Math.sqrt(delta);
            double pgcd1 = pgcd(nom1, den);
            int x1nom = (int) (nom1 / pgcd1);
            int x1den = (int) (den / pgcd1);
            // x2:
            double nom2 = -b - Math.sqrt(delta);
            double pgcd2 = pgcd(nom2, den);
            int x2nom = (int) (nom2 / pgcd2);
            int x2den = (int) (den / pgcd2);


            System.out.println("pgcd = "+String.valueOf(pgcd1)+" "+String.valueOf(pgcd2));

            System.out.println("x1 = "+String.valueOf(x1nom)+" / "+String.valueOf(x1den));
            System.out.println("x2 = "+String.valueOf(x2nom)+" / "+String.valueOf(x2den));
        }else if(delta < 0){
        }
    }


    public static double pgcd(double a, double b) {
        while (a != b) {
            if (a < b){
                b = b - a;
            }else{
                a = a - b;
            }
        }
        return a;
    }
}

Answer 1

使用BigInteger's gcd method

public static double pgcd(double a, double b) {

 return (BigInteger.valueOf((long) a).gcd(BigInteger.valueOf((long) b)).intValue());
}