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https://issues.apache.org/jira/browse/JENA-1402?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16212786#comment-16212786
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Andy Seaborne commented on JENA-1402:
-------------------------------------
The JDK8 Time API is a possibility - the support for any datatype is quite
defined and localised to a few pieces of code.
There is a requirement for the details being {{xsd:duration}} and operations -
I don't know the details of the Time API (anyone got some background?).
We might also be able to characterise the bug and find that calculating in some
other fashion (e.g. negate, reverse the substract args and negate back) avoids
problems.
> Subtracting two xsd:Duration gives incorrect results in SPARQL query
> --------------------------------------------------------------------
>
> Key: JENA-1402
> URL: https://issues.apache.org/jira/browse/JENA-1402
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 3.4.0
> Reporter: Greg Albiston
>
> There is an issue when subtracting two xsd:durations that include:
> * decimal seconds
> * non-zero minutes
> * second operand has a greater number of seconds than the first operand, i.e.
> the minutes are reduced.
> The result is a large number of minutes and incorrect seconds.
> For example:
> Integer, Larger: "PT2M3S" - "PT1M10S" = "PT0M53S" CORRECT
> Decimal, Smaller: "PT2M3.123S" - "PT1M1.123S" = "PT1M2.000S" CORRECT
> Decimal, Larger, Seconds: "PT0M3.123S" - "PT1M10.123S" = "-PT1M7.000S"
> CORRECT
> Decimal, Larger, Minutes: "PT2M3.123S" - "PT1M10.123S" = "PT883M0.020S"
> INCORRECT
> Decimal, Larger, Hours: "PT1H4M3.123S" - "PT0M10.123S" = "PT1H3883M0.020S"
> INCORRECT
> Example SPARQL:
> {code:sparql}
> SELECT ?res ?op1 ?op2
> WHERE{
> VALUES (?op1 ?op2) {
> ("PT2M3S"^^<http://www.w3.org/2001/XMLSchema#duration>
> "PT1M10S"^^<http://www.w3.org/2001/XMLSchema#duration>)
> ("PT2M3.123S"^^<http://www.w3.org/2001/XMLSchema#duration>
> "PT1M1.123S"^^<http://www.w3.org/2001/XMLSchema#duration>)
> ("PT0M3.123S"^^<http://www.w3.org/2001/XMLSchema#duration>
> "PT1M10.123S"^^<http://www.w3.org/2001/XMLSchema#duration>)
> ("PT2M3.123S"^^<http://www.w3.org/2001/XMLSchema#duration>
> "PT1M10.123S"^^<http://www.w3.org/2001/XMLSchema#duration>)
> ("PT1H4M3.123S"^^<http://www.w3.org/2001/XMLSchema#duration>
> "PT0M10.123S"^^<http://www.w3.org/2001/XMLSchema#duration>)
> }
> BIND(?op1 - ?op2 AS ?res)
> }
> {code}
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