Subject: Re: [ublas] (plus) assign a value with m(i, j) = x and with m.insert_element(i, j, x) in mapped_matrix?
From: Rutger ter Borg (rutger_at_[hidden])
Date: 2010-02-03 11:02:04
Tim Odenthal wrote:
> Why should(n't) I use m.insert_element(i,j, x) to assign an element to the
> mapped_matrix m? What is the advantage/ difference compared to using
> m(i,j) = x?
> Thanks in advance
I'm not very familiar with the mapped_matrix, but as the name states it, I
would bet on m.insert_element(i,j, x) being more efficient than m(i,j) = x.
As you may know, operator on a map is equivalent to
i.e., it inserts an empty element to be able to return a reference to
.second which then gets a value copied to if you do the assignment. With
.insert, there's just the immediate insertion. On the other hand, the
operator syntax is much more convenient, so when it's not too time
critical, you could choose for the latter.