dolfin team mailing list archive

[Johan Jansson <johanjan@xxxxxxxxxxxxxxxx>]

On Thu, Nov 10, 2005 at 09:05:57AM +0100, Johan Hoffman wrote:

...

> Interesting. How come that assembling the matrix is 3-10 times as slow as
> "assembling" the action? Is it only due to the overhead of managing the
> sparse structure?
> 
> /Johan
> 

Yes. The only real difference is the destination of the computed
values. In the matrix case they are put into a sparse matrix and in
the action case the appropriate values are summed together and put
into a vector (together with coefficient values for the action
operand).

  Johan