[
https://issues.apache.org/jira/browse/MATH-475?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12982118#action_12982118
]
Phil Steitz edited comment on MATH-475 at 1/15/11 12:48 PM:
------------------------------------------------------------
Very interesting example. How do you come up with this stuff, Sebb? :)
I tend to agree with Gilles' view that if if a and b are not distinguishable as
doubles, we don't really have any confidence in the value of abs(a - b), so the
short-circuit in the current code is better. I would say just update the
javadoc to make say something like
"Returns true if the values are indistinguishable as doubles or the difference
between them is within the range of allowed error (inclusive)."
was (Author: psteitz):
Very interesting example. How do you come up with this stuff, Sebb? :)
I tend to agree with Gilles' view that if if a and b are not distinguishable as
doubles, we don't really have any confidence in the value of abs(a - b), so the
short-circuit in the current code is better. I would say just update the
javadoc to make say something like
"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)."
> 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.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
