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https://issues.apache.org/jira/browse/MATH-1070?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13866642#comment-13866642
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Thomas Neidhart commented on MATH-1070:
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The problem you outline is quite interesting. In the case of
Precision.round(double, scale), the double value gets internally converted to a
BigDecimal, but BigDecimal loses the sign if the value is 0. This is even
documented in the javadoc:
http://docs.oracle.com/javase/7/docs/api/java/math/BigDecimal.html#BigDecimal%28java.lang.String%29
> Incorrect rounding of float
> ---------------------------
>
> Key: MATH-1070
> URL: https://issues.apache.org/jira/browse/MATH-1070
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.2
> Environment: Windows 7, IntelliJ IDEA 10.5.4.
> Reporter: Oleksandr Muliarevych
> Priority: Critical
> Fix For: 3.3
>
>
> package org.apache.commons.math3.util
> example of usage of round functions of Precision class:
> Precision.round(0.0f, 2, BigDecimal.ROUND_UP) = 0.01
> Precision.round((float)0.0, 2, BigDecimal.ROUND_UP) = 0.01
> Precision.round((float) 0.0, 2) = 0.0
> Precision.round(0.0, 2, BigDecimal.ROUND_UP) = 0.0
> Seems the reason is usage of extending float to double inside round functions
> and getting influence of memory trash as value.
> I think, same problem will be found at usage of other round modes.
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