Comment 8 for bug 956979

On Mar 16, 2012 4:35 PM, "Garth Wells" <email address hidden> wrote:
>
> On 16 March 2012 15:17, Anders Logg <email address hidden> wrote:
> > On Fri, Mar 16, 2012 at 03:04:14PM -0000, Martin Sandve Alnæs wrote:
> >> On 16 March 2012 15:49, Johan Hake <email address hidden> wrote:
> >> > This is really a duplication of bug 897372, which compared FFc and
SFC,
> >> > as SFC compiles the attached form just fine. The generated code is
much
> >> > smaller. Talking with Martin, I get the impression that FFC does not
use
> >> > the information UFL provides about the internal structure of the
> >> > different sub expressions. I got the impression that FFC lump the
whole
> >> > expression into a large string.
> >>
> >> ... for arguments to MathFunctions that is, according to earlier
> >> comments from Kristian.
> >>
> >> Material models for biological tissue often have rather complex
> >> arguments to e.g. exp.
> >>
>
> Which explode when linearised.

Sure, but not that bad. SFC managed just fine. FFC optimization might help.

FYI both SFC and FFC still use heck of alot memory. This might be rooted in
the repr are which grow quite large during a compile. Not sure how to
profile memory use in python...

Johan

> >> But Johan, did you try _with_ ffc optimization? I believe that may
> >> improve the size of the generated code.
> >
> > I thought the issue was the number of quadrature points used by FFC
> > trying to integrate the expression exactly. Does it not help to reduce
> > the quadrature order?
> >
>
> This doesn't impact on the generation time, just the runtime.
>
> The linearisation of complicated functions (fractions, etc) can really
> blow up.
>
> Garth
>
> > --
> > Anders
> >
> >
> >> Martin
> >>
> >>
> >> > Subdividing this string is probably
> >> > suboptimal compared to using the information already stored in UFL.
> >> >
> >> >
> >> > Title:
> >> > FFC generate code which cannot be compiled
> >> >
> >> > Status in FEniCS Form Compiler:
> >> > New
> >> >
> >> > Bug description:
> >> > I have a viscoelastic biomechanics form which generate an .h file
> >> > which is 45M large, with a single line length of 44M characters
long.
> >> > This wont compile with gcc. No optimization enabled at all.
> >> >
> >> > To manage notifications about this bug go to:
> >> > https://bugs.launchpad.net/ffc/+bug/956979/+subscriptions
> >>
> >
> > --
> > You received this bug notification because you are a member of FFC Core
> > Team, which is subscribed to FFC.
> > https://bugs.launchpad.net/bugs/956979
> >
> > Title:
> > FFC generate code which cannot be compiled
> >
> > To manage notifications about this bug go to:
> > https://bugs.launchpad.net/ffc/+bug/956979/+subscriptions
>
>
> --
> Garth N. Wells
> Department of Engineering, University of Cambridge
> http://www.eng.cam.ac.uk/~gnw20
>
> --
> You received this bug notification because you are a member of FFC Core
> Team, which is subscribed to FFC.
> https://bugs.launchpad.net/bugs/956979
>
> Title:
> FFC generate code which cannot be compiled
>
> Status in FEniCS Form Compiler:
> New
>
> Bug description:
> I have a viscoelastic biomechanics form which generate an .h file
> which is 45M large, with a single line length of 44M characters long.
> This wont compile with gcc. No optimization enabled at all.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ffc/+bug/956979/+subscriptions