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Thread: Math.sqrt causing general havoc

  1. #1
    Junior Member
    Join Date
    Apr 2012
    Thanked 0 Times in 0 Posts

    Default Math.sqrt causing general havoc

    The program needs to take 3 x values followed by 3 y values to create 3 points that form a triangle, then calculate the area of the triangle. I'm pretty convinced the logic is right, and it should be an easy fix.
    import java.util.*;
    public class ComputeTriangle
    	public static void main(String[]args)
    		Scanner input = new Scanner(System.in);
    		System.out.print("Please input the three points for a triangle: ");
    		double x1, x2, x3, y1, y2, y3, side1, side2, side3, s, area, calculate;
    		x1 = input.nextDouble();
    		x2 = input.nextDouble();
    		x3 = input.nextDouble();
    		y1 = input.nextDouble();
    		y2 = input.nextDouble();
    		y3 = input.nextDouble();
    		side1 = (x2-x1)/(y2-y1);
    		side2 = (x3-x1)/(y3-y1);
    		side3 = (x3-x2)/(y3-y2);
    		s = (side1 + side2 + side3)/2;
    		area = Math.sqrt(s*(s-side1)*(s-side2)*(s-side3));
    		System.out.println("The area of the triangle is: " + area);


    Please input the three points for a triangle: 1.5 -3.4 4.6 5 9.5 -3.4
    The area of the triangle is: NaN
    Press any key to continue . . .


    Can anyone help me get rid of this 'Not a Number' runtime error?

  2. #2
    Join Date
    Jan 2012
    Thanked 59 Times in 57 Posts

    Default Re: Math.sqrt causing general havoc

    Hello Garrett93!
    The javadoc says that "If the argument is NaN or less than zero, the result is NaN." You are probably passing the method a less than zero argument. You can check that out by printing every variable you have.
    Also I am not sure about your logic. The sides should be the euclidean distance between points. And the formula for computing the euclidean distance is;
    Point 1 at (x1, y1) and Point 2 at (x2, y2).
    xd = x2 - x1
    yd = y2 - y1;
    Distance = Square Root (xd ^2 + yd ^2)
    Hope it helps.

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