Re: [ublas] possible bug (probably in diagonal_matrix)

From: Gunter Winkler (guwi17_at_[hidden])
Date: 2005-06-24 03:47:49

On Friday 24 June 2005 00:13, Vardan Akopian wrote:
> Am I correct that the workaround of assigning to a dense matrix first
> (as in my sample code) has an additional cost of copying the whole
> data (in other words A is not lazily evaluated)? Is there a better
> workaround to avoid that cost?

Yes.

> >         diagonal_matrix<double> z(sz), x(sz);
> >         matrix<double> y(sz, sz);
> >         matrix<double> B = prod(z, x - y);

y -= x;
B = prod(z, -y);
y += x;

{
  // for the experienced user:
  y .minus_assign( x );
  B .assign( z, -y );
  y .plus_assign( x );
}

> Thank you. I'm new to the list, what is the normal way (if any) to
> find out if a fix has been committed to cvs (besides checking the cvs
> periodically)?

Usually the fixes are posted to this list, or at least announced. BTW. You can 
use the CVS-web interface to check files.

mfg
Gunter