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https://issues.apache.org/jira/browse/MATH-803?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13292642#comment-13292642
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Sébastien Brisard commented on MATH-803:
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I'm going to implement the suggested post-processing for the time being; this
should solve the bug. Caching of isNaN() and isInfinite() is postponed.
> Bugs in OpenMapRealVector.ebeMultiply(RealVector) and ebeDivide(RealVector)
> ---------------------------------------------------------------------------
>
> Key: MATH-803
> URL: https://issues.apache.org/jira/browse/MATH-803
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.0
> Reporter: Sébastien Brisard
> Assignee: Sébastien Brisard
>
> {{OpenMapRealVector.ebeMultiply(RealVector)}} and
> {{OpenMapRealVector.ebeDivide(RealVector)}} return wrong values when one
> entry of the specified {{RealVector}} is nan or infinity. The bug is easy to
> understand. Here is the current implementation of {{ebeMultiply}}
> {code:java}
> public OpenMapRealVector ebeMultiply(RealVector v) {
> checkVectorDimensions(v.getDimension());
> OpenMapRealVector res = new OpenMapRealVector(this);
> Iterator iter = entries.iterator();
> while (iter.hasNext()) {
> iter.advance();
> res.setEntry(iter.key(), iter.value() * v.getEntry(iter.key()));
> }
> return res;
> }
> {code}
> The assumption is that for any double {{x}}, {{x * 0d == 0d}} holds, which is
> not true. The bug is easy enough to identify, but more complex to solve. The
> only solution I can come up with is to loop through *all* entries of v
> (instead of those entries which correspond to non-zero entries of this). I'm
> afraid about performance losses.
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