[MATH-221] Result of multiplying and equals for complex numbers is wrong

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.2

Environment

OS: Debian lenny
IDE: Eclipse; Version: 3.4.0; Build id: I20080617-2000
java.runtime.version=1.6.0_04-b12
java.vendor.url=http://java.sun.com/

• Assignee: Unassigned
• Reporter: Dieter Roth
• Created: 29/Aug/08 13:31
• Updated: 23/Apr/09 02:26
• Resolved: 29/Aug/08 15:52

Description

Hi.

The bug relates on complex numbers.
The methods "multiply" and "equals" of the class Complex are involved.

mathematic background: (0,i) * (-1,0i) = (0,-i).

little java program + output that shows the bug:
-----------------------------------------------------------------------

import org.apache.commons.math.complex.*;
public class TestProg {
        public static void main(String[] args) {

                ComplexFormat f = new ComplexFormat();
                Complex c1 = new Complex(0,1);
                Complex c2 = new Complex(-1,0);

                Complex res = c1.multiply(c2);
                Complex comp = new Complex(0,-1);

                System.out.println("res:  "+f.format(res));
                System.out.println("comp: "+f.format(comp));

                System.out.println("res=comp: "+res.equals(comp));
        }
}

-----------------------------------------------------------------------

res: -0 - 1i
comp: 0 - 1i
res=comp: false

-----------------------------------------------------------------------

I think the "equals" should return "true".
The problem could either be the "multiply" method that gives (-0,-1i) instead of (0,-1i),
or if you think thats right, the equals method has to be modified.

Good Luck
Dieter