Ah, I see, you just pointed to the issue, sorry misread your mail.

The problem is that checking matrices and vectors for equality is a very
costly operation (you have to compare at least all non-zero entries).
For that reason, we did not implement equals correctly (which is in
general a very bad thing).

We advise users not use vectors and matrices in places where equality
checks on them are necessary (e.g. in a HashSet or as key in a HashMap)

A way to manually check the equivalence of two dense matrices is to
compare all entries.

--sebastian


On 29.12.2013 17:49, Chameera Wijebandara wrote:
> Sebastian,
> Yes It's not enought to check the reference. i mean DenseMatrix*.*equals()
> methord does that and it cannot use for check equity is that wrong?
> 
> 
> 
> On Sun, Dec 29, 2013 at 8:40 AM, Sebastian Schelter <[email protected]> wrote:
> 
>> Chameera,
>>
>> This is wrong. It's not enought to check the reference, two different
>> instances can be semantically equivalent,
>>
>> A dense matrix represents its entries in a two dimensional double array.
>> You have to check for the equality of these arrays.
>>
>> --sebastian
>>
>> On 29.12.2013 17:14, Chameera Wijebandara wrote:
>>> Hi Tharindu
>>>
>>> In the DenseMatrix class does not implement equals method so it use
>>> Object.equals witch check the reference.
>>> You have implement equals method by overriding Object.equals method.
>>>
>>> Thanks
>>>   Chameera
>>>
>>
>>
> 
> 

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