dolfin team mailing list archive

[Robert Kirby <kirby@xxxxxxxxxxxxxxx>]

1.) If this is true, why are we working on ferari?
2.) Relative cost of assembly versus solve depends on:
	- how good your sparse matrix implementation is
	- how good your solvers are (e.g. Jacobi's method versus optimally 
preconditioned CG)
3.) My point is that we are trying to optimize matrix assembly in its 
own right.  In order to do this, we need a linear algebra package that 
assembles matrices as fast as possible.  In order to do this, it will 
need a coarser granularity than "here's an entry, do something with it" 
 -- The granularity of "Here is a local matrix and the global indices, 
put them in" will afford a good library more opportunities to do better 
than inserting each item individually.

Remember that Anders picked up a factor of 10 moving away from a naive 
form interpreter to actual compiled code.  I wonder how much he will 
pick up optimizing the matrix assembly

Robert C. Kirby
Assistant Professor
Department of Computer Science
The University of Chicago
http://people.cs.uchicago.edu/~kirby

On Oct 26, 2004, at 4:05 AM, Matthew Knepley wrote:

> ridg@xxxxxxxxxxxxxxx (Ridgway Scott) writes:
> > How does the form of the API affect the efficiency of the linear
> > algebra? It would seem that the overhead of the call would be
> > small compared to the cost of doing a solve.
>     This is true, and I think is the underpinning of Rob's argument.
>
>          Matt
> > 				Ridg
> --
> "Failure has a thousand explanations. Success doesn't need one" -- Sir 
> Alec Guiness