[ublas] Aliasing for += and -=

From: christopher diggins (cdiggins_at_[hidden])
Date: 2005-06-12 11:41:15

>From the FAQ:

"The first assigned seemes to be at least twice as fast as the second 
assignement, although the same algorithm is used. Why? UBLAS always expects 
that the right hand side of an expression can have common storage with the 
left hand side, i.e. that there is aliasing. Thus uBLAS first evaluates the 
right hand side into a temporary vector and then applies the changes to the 
left hand side."

I mentioned this before, and I'll say it again: A straightforward 
implementation of += and -= is not affected by aliasing. This is trivial to 
fix. I find it unacceptable that the library can not do such a simple task 
correctly.

Christopher Diggins
http://www.cdiggins.com