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From "Sebb (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MATH-475) MathUtils.equals(double, double, double) does not agree with Javadoc
Date Mon, 17 Jan 2011 12:15:43 GMT

    [ https://issues.apache.org/jira/browse/MATH-475?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12982613#action_12982613
] 

Sebb commented on MATH-475:
---------------------------

The consensus seems to be to update the Javadoc as follows:

"Returns true if there is no double value strictly between the arguments or the difference
between them is within the range of allowed error (inclusive)."

I am happy with that.


> MathUtils.equals(double, double, double) does not agree with Javadoc
> --------------------------------------------------------------------
>
>                 Key: MATH-475
>                 URL: https://issues.apache.org/jira/browse/MATH-475
>             Project: Commons Math
>          Issue Type: Bug
>            Reporter: Sebb
>
> MathUtils.equals(double, double, double) does not agree with its Javadoc.
> The Javadoc says:
> "Returns true if both arguments are equal or within the range of allowed error (inclusive)."
> However the following test fails:
> {code}
> double top=1.7976931348623184E16;
> double pen=1.7976931348623182E16;
> double diff=Math.abs(top-pen);
> assertTrue(MathUtils.equals(top, pen, 1.0)); // OK - implies the difference is <=
1.0
> assertTrue("expected < 1.0, but was: "+diff,diff <= 1.0); // reports: expected
< 1.0, but was: 2.0
> {code}
> This discrepancy is because the equals(double, double, double) method also checks to
see if the numbers are within one ULP of each other.
> Either the Javadoc needs to be corrected, or the code needs to be corrected to drop the
ULP comparison.

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