commons-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Yannick TANGUY (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MATH-866) New method to compute relative deviation between two floating numbers
Date Thu, 20 Sep 2012 08:15:07 GMT
Yannick TANGUY created MATH-866:
-----------------------------------

             Summary: New method to compute relative deviation between two floating numbers
                 Key: MATH-866
                 URL: https://issues.apache.org/jira/browse/MATH-866
             Project: Commons Math
          Issue Type: Improvement
    Affects Versions: 3.1
            Reporter: Yannick TANGUY


A new method to compute a relative deviation would be very useful.

In order to handle properly odd values (O+,0-,NaN,Infinity), we suggest to call first the
classical equals() method (strict equality, using one ulp as a threshold) and then the relative
tolerance.

Here is the code we use : 

  public static boolean equalsWithRelativeTolerance(final double x, final double y, final
double eps) {

        // Initialisation
        boolean isEqual = false;

        // very close (including both equals 0.0) case
        if (equals(x, y)) {
            isEqual = true;
        }
        // common case
        else {
            // Relative difference computation
            final double absoluteMax = FastMath.max(FastMath.abs(x), FastMath.abs(y));
            final double relativeDifference = FastMath.abs((x - y) / absoluteMax);

            //test
            if (relativeDifference < eps) {
                isEqual = true;
            }
        }
        return isEqual;
    }


--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message