[MATH-803] Bugs in RealVector.ebeMultiply(RealVector) and ebeDivide(RealVector)

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0
• Fix Version/s: 3.3
• Assignee: Unassigned
• Reporter: Sebastien Brisard
• Created: 09/Jun/12 18:51
• Updated: 19/May/14 15:13
• Resolved: 20/Feb/14 15:58

Description

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

    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;
    }

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.