"Michael Ulm" <michael.ulm / isis-papyrus.com> wrote in message 
news:4506685A.8000309 / isis-papyrus.com...
> Just Another Victim of the Ambient Morality wrote:
>
>> "MonkeeSage" <MonkeeSage / gmail.com> wrote in message 
>> news:1158024640.933843.82830 / i42g2000cwa.googlegroups.com...
>>
>>>Dave Burt wrote:
>>>
>>>>If you want a matrix-like data structure (rather than a mathematical
>>>>matrix), why not use an array of arrays?
>>>
>>>A mathematical matrix is just a dimensional arrangement of data into
>>>"rows" and "columns", thus allowing for certain algorithmic
>>>relationships to be defined and applied (e.g., canonical
>>>decompositions). Every matrix (i.e., the actual matrix considered as a
>>>complex value) is immutable and has a unique identity, just like every
>>>number -- that's true -- but they can also be permuted or otherwise
>>>transformed into different matrices. Why should one have to do that
>>>constructively (i.e., construct a new matrix "from scratch"), rather
>>>than destructively (i.e., change the existing matrix "in place"). Think
>>>of it like this: n = 1; n = n + 1 -- even though the number 1 is
>>>immutable and has a unique identity, the reference to it is not, and
>>>can thus be destructively altered by assignment with the result that it
>>>refers to new identity. It would be a pain to have to do o = n + 1, p =
>>>n + 2 (i.e., creating new references every time the data changes), just
>>>because 1 is immutable. Why should a matrix be any different? Mabye I'm
>>>missing something...
>>
>>
>>     As far as I can tell, matrices are no different.  Your example shows 
>> that 1 is immutable but references to it can be re-assigned, so you can 
>> do:
>>
>> n = 3
>> n = n + 1
>>
>>
>>     Matrices are no different and, so, you can do:
>>
>>
>> n = Matrix.scalar(2, 3)
>> n = n + Matrix.I(2)
>>
>>
>>     In both cases, the "number" types are immutable but the references 
>> to them are not, as you say.  They both work exactly the same way.  What 
>> are you trying to say?
>
> I think he's trying to say, that there is no rational reason for
> leaving out the []= operator, and I agree.

    Well, yeah, I got that.  It's just that he spent this whole paragraph 
on a rationale that wasn't true so I was wondering what he was really 
trying to get at for his rationale...