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

From: Victor A. Wagner, Jr. (vawjr_at_[hidden])
Date: 2002-05-03 11:11:06

At Wednesday 2002/05/01 12:17, you wrote:
>----- Original Message -----
>From: "Toon Knapen" <toon.knapen_at_[hidden]>
>To: <boost_at_[hidden]>
>Sent: Tuesday, April 30, 2002 6:09 PM
>Subject: [boost] ublas: matrix clear() and operator=
>
>
> > Currently, the matrices can be clear()-ed such that all elements are set
>to
> > 0. I would find it even more convenient to be able to use
> > operator=(some_value_type) to assign a specific value to all the entries
>in
> > the matrix.
>
>How would you define the semantics of such an assignment operator for sparse
>matrices?

It seems to me the whether the matrix is implemented as a 2D array or held 
in some sparse implementation, ALL of the entries should now have 
(some_value_type).

As an implementation detail for the sparse representation, there is nothing 
sacred about calling the value of an unheld entry zero(0), it could be any 
value.  One possible implementation of this operator would to be to "empty" 
the sparse cells which exist and set the "default value" appropriately.

> > But I figure there's some good reason one has to use clear()
> > instead of operator=() ?
>
>Do you think, it would be worthy to add something like zero_vector<> and
>zero_matrix<> to allow for syntactic sugar like m = zero_matrix<>()?
>
>Regards
>
>Joerg
>
>
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Victor A. Wagner Jr.      http://rudbek.com
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