Re: [ublas] [uBlas] Fastest way to change sing of matrix

Subject: Re: [ublas] [uBlas] Fastest way to change sing of matrix
From: oswin krause (oswin.krause_at_[hidden])
Date: 2013-04-16 07:05:37

Hi,

oh i somehow missed the part in the bracket. sorry. While you are right 
that it strictly violates the assumption, you know that blas1 calls 
(aside from transpose) can't alias.

On 16.04.2013 12:29, dariomt wrote:
>
>> >       As i assume A to be a small matrix:
> I did say it is very large.
>
>
>> >       noalias(A)=-A
>> >       fixes everything.
> Doesn't that suggestion break the assumptions of noalias? From the docs: "If
> you know for sure that the left hand expression and the right hand
> expression have no common storage". Well, the lhs and the rhs both reference
> the same matrix object!
>
> How is that guaranteed to work?
>