[firedrake] Parallel issues and projection issues

[Lawrence Mitchell]

On 16/02/17 18:08, William Booker wrote:
> Dear Lawrence,
> 
> "I note in passing that your code will be very slow because you call
> solve in a loop over-and-over.  You should refactor it to use a
> LinearVariationalSolver.  This notebook
> https://nbviewer.jupyter.org/github/firedrakeproject/firedrake/blob/master/docs/notebooks/example-burgers.ipynb
> 
> describes how (and why) you need to do this."
> 
> Would it be possible to use this Solver, .solve() method if a part of
> the weak form was time dependant.
> I have a body force included in the weak form  now.

Yes.

> If I created a solver, and then called .solve() while using .assign to
> change the value of my body force,
> would you still expect run time to be faster or would this better for
> non autonomous matrices.

It will still be faster.  You will only be recomputing values, not
allocating and deallocating the matrices and rederiving symbolic
information (which is not free).

Lawrence

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