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https://issues.apache.org/jira/browse/LANG-381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12547665
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Phil Steitz commented on LANG-381:
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The comparator has to impose a total ordering, so it has to put NaN somewhere.
The min/max functions do not have to do this - i.e., we could define the
contract of min/max to be to return NaN iff there are no non-NaN values in the
array, so NaNs are effectively excluded. This is what we did in [math]. See,
e.g.,
http://commons.apache.org/math/api-1.1/org/apache/commons/math/stat/StatUtils.html#min(double[],%20int,%20int)
> 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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