CODEWITHSUNDEEP
javasign
Roman Panaget
Roman Panaget

Reputation: 2428

Having problems with negative signed numbers

I'm making a simple test in java, (i'm a begineer) and i was trying to make a program that calculates the discriminate of a second degree equation and displays the results, but when i change the sign of nom1 and nom2, the program doesn't displays any result, i've made some tests and i'm sure that the problem is there but i don't know how to resolve it. Any help is welcome.

Here is my code: 

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;
    }
}

Upvotes: 2

Views: 95

Answers (1)

Ravi Yenugu
Ravi Yenugu

Reputation: 3898

Use BigInteger's gcd method

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

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

Upvotes: 1

Related Questions