Re: [boost] ublas: matrix clear() and operator=

From: Matthias Troyer (troyer_at_[hidden])
Date: 2002-05-06 02:57:09

On Saturday, May 4, 2002, at 08:13  PM, Toon Knapen wrote:

> On Friday 03 May 2002 16:18, Joerg Walter wrote:
>> If we use a scalar
>> assignment operator, we could assume a matrix layout. It seems 
>> reasonable
>> to assume a dense layout. The main point now is, that the proposed
>> assignment operator is rather useless, if one assigns a non zero 
>> scalar to
>> a sparse matrix assuming dense matrix layout.
>>
>> IOW I'd like to keep scalars, vectors and matrices separate ;-)
> Thinking of it again, I agree with you.
> I was looking at the BLAST specs to get some inspiration but found no 
> similar
> operation directly (of course you can get the same result doing m*= 0 
> but
> this is doubtly the best way to do it).

No, m*=0 does not work, as far as I know. At least in my experience
(but it might be a broken implementation), if the uninitialized
matrix contains NaN, multiplying the NaN with 0 is still NaN and not 0.

Matthias