ufl team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Sun, Apr 19, 2009 at 02:02:57PM +0200, Martin Sandve Alnæs wrote:
> With some renaming, we now have:
> 
> extract_max_quadrature_element_degree:
> Returns max degree of found quadrature elements, None with no
> quadrature elements

Sounds good.

> estimate_quadrature_degree:
> Uses the formula 2*v.element().degree() for linear forms,
> v.element().degree()+u.element().degree() for bilinear forms,
> don't know if we need this? Returns None for functionals now.
> The form compilers could have an option to use this variant.

Is it to be used as a fallback if the others fail?

> estimate_max_polynomial_degree:
> Estimates the highest polynomial degree of the expression.
> It is an estimate since not all operators are polynomials.

Does it return something sensible even if the expression is not a
polynomial?

If so, then estimate_quadrature_degree may not be needed.

It would be enough for a form compiler to do this:

  quadrature_degree = extract_max_quadrature_element_degree(integral)
  if quadrature_degree is None:
      quadrature_degree = estimate_max_polynomial_degree(integral)

Perhaps this should be in UFL?

-- 
Anders


> I've added a unit test, but only for some basic cases.
> 
> Martin
> 
> 
> 
> On Sun, Apr 19, 2009 at 8:46 AM, Anders Logg <logg@xxxxxxxxx> wrote:
> > On Sun, Apr 19, 2009 at 02:11:12PM +0800, Garth N. Wells wrote:
> >>
> >>
> >> Anders Logg wrote:
> >>> On Fri, Apr 17, 2009 at 12:02:04PM +0200, Martin Sandve Alnæs wrote:
> >>>> Take a look at
> >>>>   ufl/sandbox/algorithmtests/degree_estimation.py
> >>>> just added.
> >>>>
> >>>> Is this good enough for the initial version?
> >>>> It handles mixed elements by using the max
> >>>> degree of subelements, and nonlinear operators
> >>>> by just using the degree of the operands.
> >>>> Should work fine for most forms where accurate
> >>>> estimation is possible.
> >>>>
> >>
> >> Should it be called 'estimate_max_poly_order' rather than
> >> 'estimate_max_quadrature_order'?
> >
> > My suggestion would be
> >
> >  estimate_max_polynomial_degree
> >
> > Then it's very clear what it is.
> >
> >>>> I'll add it into UFL soon.
> >>>>
> >>>> Martin
> >>>
> >>> It looks good to me, but I haven't tried it.
> >>>
> >>> UFL now seems to have at least three ways to estimate the quadrature
> >>> degree:
> >>>
> >>>   extract_quadrature_order
> >>
> >> This gets the order of a quadrature element.
> >
> > ok. I find the naming a bit confusing. How about we change the name of
> > this as well. Then we have two functions:
> >
> >  estimate_max_polynomial_degree
> >  extract_max_quadrature_element_degree
> >
> > Maybe the first one should also be named 'extract'. Or is it
> > 'estimate' because it might only make a qualified guess if the
> > integrand is not a polynomial? So we could have
> >
> >  extract_max_polynomial_degree
> >  extract_max_quadrature_element_degree
> >
> > Then it would be very clear what these two functions do.
> >
> > Martin?
> >
> >>>   estimate_quadrature_order
> >>
> >> I don't follow exactly what this function is doing.
> >>
> >>>   estimate_max_quad_degree
> >
> > This is still in the sandbox.
> >
> > Do you have a good test example that can be added to the demos so we
> > verify things work as expected?
> >
> >
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