CODEWITHSUNDEEP
javaappletcomputer-science
Khanak
Khanak

Reputation: 15

Create a java program to solve quadratic equations

Solving a quadratic equation

I have the following written down so far. I am not sure on how to introduce the second method 

public static void main(string args[]){

}

public static  double quadraticEquationRoot1(int a, int b, int c) (){

}

if(Math.sqrt(Math.pow(b, 2) - 4*a*c) == 0)
{
    return -b/(2*a);
} else {
    int root1, root2;
    root1 = (-b + Math.sqrt(Math.pow(b, 2) - 4*a*c)) / (2*a);
    root2 = (-b - Math.sqrt(Math.pow(b, 2) - 4*a*c)) / (2*a);
    return Math.max(root1, root2);  
}

}

Upvotes: 1

Views: 42195

Answers (3)

Ahmed Rakha
Ahmed Rakha

Reputation: 210

package QuadraticEquation;

import javax.swing.*;

public class QuadraticEquation {
   public static void main(String[] args) {
      String a = JOptionPane.showInputDialog(" Enter operand a :  ");
      double aa = Double.parseDouble(a);
      String b = JOptionPane.showInputDialog(" Enter operand b :  ");
      double bb = Double.parseDouble(b);
      String c = JOptionPane.showInputDialog(" Enter operand c :  ");
      double cc = Double.parseDouble(c);
      double temp = Math.sqrt(bb * bb - 4 * aa * cc);
      double r1 = ( -bb + temp) / (2*aa);
      double r2 = ( -bb -temp) / (2*aa);
      if (temp > 0) {
            JOptionPane.showMessageDialog(null, "the equation has two real roots" +"\n"+" the roots are : "+  r1+" and " +r2);

        }
      else if(temp ==0) {
            JOptionPane.showMessageDialog(null, "the equation has one root"+  "\n"+ " The root is :  " +(-bb /2 * aa));

        }

      else{

            JOptionPane.showMessageDialog(null, "the equation has no real roots !!!");
        }
    }        
}

Upvotes: 0

apnorton
apnorton

Reputation: 2440

Firstly, your code won't compile--you have an extra } after the start of public static double quadraticEquationRoot1(int a, int b, int c) ().

Secondly, you aren't looking for the correct input types. If you want input of type double, make sure you declare the method appropriately. Also be careful of declaring things as int when they could be doubles (for example, root1 and root2).

Thirdly, I don't know why you have the if/else block--it would be better to simply skip it, and only use the code that is currently in the else part.

Finally, to address your original question: Simply create a separate method and use Math.min() instead of Math.max().

So, to recap in code:

public static void main(string args[]){

}

//Note that the inputs are now declared as doubles.
public static  double quadraticEquationRoot1(double a, double b, double c) (){    
    double root1, root2; //This is now a double, too.
    root1 = (-b + Math.sqrt(Math.pow(b, 2) - 4*a*c)) / (2*a);
    root2 = (-b - Math.sqrt(Math.pow(b, 2) - 4*a*c)) / (2*a);
    return Math.max(root1, root2);  
}

public static double quadraticEquationRoot2(double a, double b, double c) (){    
    //Basically the same as the other method, but use Math.min() instead!
}

Upvotes: 5

DanZimm
DanZimm

Reputation: 2578

Well why don't you try to use the same exact algorithms but then use Math.min in your return statement?

Also, note that you're not taking into account whether or not $b$ is negative in your first if statement. In other words you simply return $-b / 2a$ but you don't check if $b$ is negative, if it isn't then this is actually the smaller of the two roots not the larger. Sorry about that! I misinterpreted what was going on xD

Upvotes: 3

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