dolfin team mailing list archive

[Matthew Knepley <knepley@xxxxxxxxxxx>]

"Robert C.Kirby" <kirby@xxxxxxxxxxxxxxx> writes:
> Of course ferari << quadrature, but if even quadrature << solver, why bother optimizing it?
        I wouldn't. I msut be getting confused with the discussion.
> 
> Both/and.  First, there is the mathematical issue (this is tantamount and has the biggest impact).  But even if you have
> an optimal preconditioner, a crappy implementation of the matrix-vector product (e.g. (i,j) index storing by unsorted
> lists), you will have a huge difference in performance among implementations.
        I wasn't allowing for anything that crappy. Most common implementations
are fine, but someone could still screw it up. An excellent arugment for using
existing libraries.
> 
> Yes, but as you say in your response to Anders, you need an interface that is optimizable.  Setting values one at a time
> is not such an interface.
        Yep.

                Matt
-- 
"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec Guiness