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From "Henri Yandell (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (LANG-381) NumberUtils.min(floatArray) returns wrong value if floatArray[0] happens to be Float.NaN
Date Sun, 02 Dec 2007 04:44:43 GMT

    [ https://issues.apache.org/jira/browse/LANG-381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12547572
] 

bayard edited comment on LANG-381 at 12/1/07 8:43 PM:
-------------------------------------------------------------

Last spammy comment on this I promise....

This seems like a confusing bit. If we look at the JDK, we get:

Math.min(Double.NaN, 1.0) => NaN
Math.max(Double.NaN, 1.0) => NaN

However:

Double.compare(Double.NaN, 1.0) => 1
Double.compare(1.0, Double.NaN) => -1

That is, the JDK is not without its problems. It seems to me that the min/max methods need
to take their leads from the JDK ones. So the (double, double, double) ones are implicitly
correct as they are nothing more than wrappers for a couple of Math.min calls.

This bug is not that NaN is returned, but that 1.2 is returned.

ie) If NaN is found in min(double[]), then the min is NaN.
The same holds for max - it should never return 42.0 in the above example.

Thoughts?

      was (Author: bayard):
    Last spammy comment on this I promise....

This seems like a confusing bit. If we look at the JDK, we get:

Math.min(Double.NaN, 1.0) => NaN
Math.max(Double.NaN, 1.0) => NaN

However:

Double.compare(Double.NaN, 1.0) => -1
Double.compare(1.0, Double.NaN) => 1

That is, the JDK is not without its problems. It seems to me that the min/max methods need
to take their leads from the JDK ones. So the (double, double, double) ones are implicitly
correct as they are nothing more than wrappers for a couple of Math.min calls.

This bug is not that NaN is returned, but that 1.2 is returned.

ie) If NaN is found in min(double[]), then the min is NaN.
The same holds for max - it should never return 42.0 in the above example.

Thoughts?
  
> NumberUtils.min(floatArray) returns wrong value if floatArray[0] happens to be Float.NaN
> ----------------------------------------------------------------------------------------
>
>                 Key: LANG-381
>                 URL: https://issues.apache.org/jira/browse/LANG-381
>             Project: Commons Lang
>          Issue Type: Bug
>    Affects Versions: 2.3
>            Reporter: Thomas Vandahl
>             Fix For: 2.4
>
>
> The min() method of NumberUtils returns the wrong result if  the first value of the array
happens to be Float.NaN. The following code snippet shows the behaviour:
>         float a[] = new float[] {(float) 1.2, Float.NaN, (float) 3.7, (float) 27.0, (float)
42.0, Float.NaN};
>         float b[] = new float[] {Float.NaN, (float) 1.2, Float.NaN, (float) 3.7, (float)
27.0, (float) 42.0, Float.NaN};
>         
>         float min = NumberUtils.min(a);
>         System.out.println("min(a): " + min); // output: 1.2
>         min = NumberUtils.min(b);
>         System.out.println("min(b): " + min); // output: NaN
> This problem may exist for double-arrays as well. 
> Proposal: Use Float.compare(float, float) or NumberUtils.compare(float, float) to achieve
a consistent result.

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