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Posted to dev@velocity.apache.org by "Claude Brisson (Jira)" <de...@velocity.apache.org> on 2021/02/27 20:30:00 UTC
[jira] [Closed] (VELTOOLS-182) MathTool.max longtime bug with args
(0,0)
[ https://issues.apache.org/jira/browse/VELTOOLS-182?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Claude Brisson closed VELTOOLS-182.
-----------------------------------
> MathTool.max longtime bug with args (0,0)
> -----------------------------------------
>
> Key: VELTOOLS-182
> URL: https://issues.apache.org/jira/browse/VELTOOLS-182
> Project: Velocity Tools
> Issue Type: Bug
> Components: GenericTools
> Affects Versions: 2.0
> Reporter: Sanford Whiteman
> Assignee: Claude Brisson
> Priority: Major
> Fix For: 3.1
>
>
> It appears that {{$math.max}} has had a bug since at least 2.0, or at least I'm at a loss as to why the observed behavior would be expected, and it doesn't appear to be documented.
>
> {code:java}
> $math.max(0,0) {code}
>
> returns
>
> {code:java}
> 4.9E-324{code}
>
> that is, Double.MIN_VALUE.
>
> It's easy to see why in the source. Using [3.0|https://apache.googlesource.com/velocity-tools/+/trunk/velocity-tools-generic/src/main/java/org/apache/velocity/tools/generic/MathTool.java#377] here, we see:
>
> {code:java}
> public Number max(Object... nums)
> {
> double value = Double.MIN_VALUE;
> Number[] ns = new Number[nums.length];
> for (int i=0; i<nums.length; i++)
> {
> Number n = toNumber(nums[i]);
> if (n == null)
> {
> return null;
> }
> value = Math.max(value, n.doubleValue());
> ns[i] = n;
> }
> return matchType(value, ns);
> }
> {code}
>
> So rather than delegating to {{Java.lang.Math.max}} directly, each iter takes the {{Math.max}} of the current value and Double.MIN_VALUE. Ergo, if the arguments are 0, that's always < Double.MIN_VALUE, so the result is in turn Double.MIN_VALUE.
> The same goes for {{$math.max(0)}} (just one arg) but at least that could be considered a usage error.
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