I have overridden plus() method in SparseVector. Inorder to do this, I need to add a method called addCardinality().
Also, I found that in dot() method, it shouldn't throw cardinalityException. So, I removed that condition. Please review the code.

Thanks
Pallavi

Instead of using the following explicitly, you might consider using Java5 style notation, as vector implements Iterable:

> java.util.Iterator<Vector.Element> iterator = x.iterator();
> while (iterator.hasNext()) {
> Vector.Element element = iterator.next();

I haven't tried it, but it should be possible to use the following expression:

for (Vector.Element element : x) {
...
}

I always find this style easier to read than the explicit use of iterator()

Isabel

You say you need to modify the cardinality. I'm not sure about what has been said about the constraints of Vector modifiers, but the code seems rather static about Vectors being compatible from the start.

[deleted some stuff here that made no sense]

Isabel: Sure, I will make those changes.

Karl: I couldn't get. Can you please elaborate it?

also added divide method

changed to Java5 notation style.
Also added divide method for sparse vector.

Could you please also add a unit test that shows, that the current implementation is broken but your version works?

I have added unit tests to show that the current implementation breaks for sparse vector plus, dot and divide operation. and my version works.

I misunderstood the sparse vector representation. I agree that the cardinality exception should be thrown if two sparse vectors' cardinality is not same. But, my implementation still holds and optimizes the computation of divide and plus operation over sparse vectors.

I have restored the cardinality check in dot method and also added cardinality check for plus method and so updated unit tests accordingly. As this code is optimization of existing code, the previous unit tests holds.

I checked, and at this point AbstractVector already does what this patch did, through use of iterateNonZero(). Marking this basically obsoleted.