
Ublas : 
From: Gross, Steve (SGross_at_[hidden])
Date: 20070322 11:13:10
I've been testing the performance of ublas's matrix multiplication. I
encountered a behavior that I don't quite understand. Consider the
following code snippet:
Ublas::matrix<double> m1(100, 100), C(100, 100);
Ublas::Prod(m1, m1)
c = ublas::prod(m1, m1)
The second line and the third line are identical, except that in the
third line I assign the result of the product operation to a presized
matrix. The second line appears to take almost no time to execute (0
millisecs, that is). The third line takes a nonzero amount of time to
execute, however.
What's going on here? Is the product operation super crazy fast, but the
matrix assignment part slow?
Steve