Here's what I've found out so far:

- The tabulate_tensor functions in your example should be equal, it's
actually the signature that is correct.

- The bug is independent of ffc representation (quadrature, tensor, and
uflacs),

- In uflacs I see some tables for CG2 values are different which they
shouldn't be. Since not all of the table generation is shared between
representations, this narrows it down.

- My strong hunch now is that some place in FFC, related to tabulation of
element values from FIAT, access UFL elements  without replacing with the
mapped element. I have checked in a slightly simpler script in uflacs that
cause a failure, which could be related.

Martin


On 11 March 2013 19:59, Johan Hake <email address hidden> wrote:

> The two forms generates the same signature, but different
> tabulate_tensor functions. Something is fishy with form_data.signature.
>
> instant-clean
> run script
> out-comment region and run instant-clean
>
> from dolfin import *
>
> mesh = UnitSquareMesh(16,16)
> V = FunctionSpace(mesh, 'CG', 2)
> w = TestFunction(V)
> Pv = TrialFunction(V)
> a = inner(w, Pv)*dx
> A = assemble(a)
> u = Function(V)
>
> # Out-comment next region and run instant clean to reproduce bug
> f = Expression("x[0]*x[0] + 2*x[1]*x[1]")
> L = inner(w, f)*dx
> b = assemble(L)
> print "Signature", L.form_data().signature
> solve(A, u.vector(), b)
> print u.vector().norm("l2")
> # Out-comment to here.
>
> f2 = Expression("x[0]*x[0] + 2*x[1]*x[1]", degree=2)
> L = inner(w, f2)*dx
> b = assemble(L)
> solve(A, u.vector(), b)
> print "Signature", L.form_data().signature
> print u.vector().norm("l2")
>
>
> Happy bug hunting :)
>
> Johan
>
>
> On 03/11/2013 07:28 PM, Martin Sandve Alnæs wrote:
> > I would look at the instant side. Or in ffc.jitobject. repr of a form is
> > not used anywhere.
> >
> > Martin
> > Den 11. mars 2013 18:20 skrev "Johan Hake" <email address hidden>
> > følgende:
> >
> >> On 03/11/2013 04:31 PM, Marie Rognes wrote:
> >>> On 03/11/2013 04:07 PM, Johan Hake wrote:
> >>>> Are you sure this is a bug?
> >>>
> >>> Pretty sure, yes.
> >>>
> >>>> In the first example the Expression is generated without setting the
> >>>> degree. If this is auto chosen to 2 it should make perfectly sense
> they
> >>>> give the same results.
> >>>
> >>> Yes. But the problem is that the Expression with degree=2 gives
> >>> different results depending on what has been compiled before it.
> >>>
> >>>> Change degree to something else and you will have
> >>>> a different results.
> >>>
> >>> Did you read the problem carefully? Look at (*) and (**).  Both of
> these
> >>> correspond to setting degree=2 explicitly. The numbers should therefore
> >>> be the same. They are not, which is highly disturbing. (*) is produced
> >>> after doing instant-clean, running with auto degree, and running with
> >>> degree = 2 (which seems to reuse the auto degree code); while (**) is
> >>> produced after doing instant-clean and directly running with degree=2.
> >>
> >> Ok, I see it now. Pretty disturbing yes.
> >>
> >> How can we find out what degree is chosen for the expression when it is
> >> autogenerated? Is it during preprocess? Is it still so that it is the
> >> repr of the preprocessed form that determines if a form will get
> >> recompiled?
> >>
> >> from dolfin import *
> >>
> >> mesh = UnitSquareMesh(16,16)
> >> V = FunctionSpace(mesh, 'CG', 2)
> >> w = TestFunction(V)
> >> f = Expression("x[0]*x[0] + 2*x[1]*x[1]")
> >> L = inner(w, f)*dx
> >> b = assemble(L)
> >>
> >> print "Preprocessed:", repr(L.form_data().preprocessed_form)
> >> print "Not preprocessed:", repr(L)
> >>
> >> Prints:
> >> Preprocessed: Form([Integral(Product(Argument(FiniteElement('Lagrange',
> >> Domain(Cell('triangle', 2), 'triangle_multiverse', 2, 2), 2, None), -2),
> >> Coefficient(FiniteElement('Lagrange', None, None, None), 0)), 'cell',
> >> 'otherwise', None, None)])
> >> Not preprocessed:
> >> Form([Integral(Product(Argument(FiniteElement('Lagrange',
> >> Domain(Cell('triangle', 2), 'triangle_multiverse', 2, 2), 2, None), -2),
> >> Coefficient(FiniteElement('Lagrange', None, None, None), 0)), 'cell',
> >> 'everywhere', None, None)])
> >>
> >> Where it is clear that the Coefficient of the first form has not got any
> >> degree. Shouldn't it have got one?
> >>
> >> Johan
> >>
> >>
> >>> --
> >>> Marie
> >>>
> >>>
> >>>> Johan
> >>>>
> >>>> On 03/11/2013 10:06 AM, Marie Rognes wrote:
> >>>>> Public bug reported:
> >>>>>
> >>>>> There seems to be something seriously wrong with either DOLFIN-FFC
> jit
> >>>>> compilation or caching or instant.
> >>>>>
> >>>>> To reproduce, for instance consider the following code snippet and do
> >>>>> the following
> >>>>>
> >>>>> (1): Run instant-clean
> >>>>>
> >>>>> (2): Run script unmodified.
> >>>>>
> >>>>> Output is:
> >>>>>
> >>>>> Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>>>> Calling DOLFIN just-in-time (JIT) compiler, this may take some time.
> >>>>> Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>>>> Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>>>> Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>>>> 40.4757877531
> >>>>>
> >>>>> (3) Uncomment commented lines and run.
> >>>>>
> >>>>> Output is:
> >>>>>
> >>>>> Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>>>> 40.4757877531
> >>>>> Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>>>> 40.4757877531 (*)
> >>>>>
> >>>>> (4) Run instant-clean, comment out lines defining f, g, and 1st
> print.
> >>>>> Run.
> >>>>>
> >>>>> Output is
> >>>>> Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>>>> Calling DOLFIN just-in-time (JIT) compiler, this may take some time.
> >>>>> Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>>>> Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>>>> Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>>>> 40.490263582 (**)
> >>>>>
> >>>>> Problem: The last two floats, tagged by (*) and (**), should be the
> >>>>> same: they are not.
> >>>>>
> >>>>> Code snippet:
> >>>>>
> >>>>> --
> >>>>>
> >>>>>
> >>>>> from dolfin import *
> >>>>> mesh = UnitSquareMesh(16,16)
> >>>>> V = FunctionSpace(mesh, 'CG', 2)
> >>>>>
> >>>>> f = Expression("x[0]*x[0] + 2*x[1]*x[1]")
> >>>>> g = project(f, V)
> >>>>> print g.vector().norm("l2")
> >>>>>
> >>>>> #f2 = Expression("x[0]*x[0] + 2*x[1]*x[1]", degree=2)
> >>>>> #g2 = project(f2, V)
> >>>>> #print g2.vector().norm("l2")
> >>>>>
> >>>>>
> >>>>> --
> >>>>>
> >>>>> ** Affects: dolfin
> >>>>>       Importance: Undecided
> >>>>>           Status: New
> >>>>>
> >>>
> >>
> >> --
> >> You received this bug notification because you are a member of DOLFIN
> >> Core Team, which is subscribed to DOLFIN.
> >> https://bugs.launchpad.net/bugs/1153508
> >>
> >> Title:
> >>   Strange results in JIT compilation
> >>
> >> Status in DOLFIN:
> >>   Confirmed
> >>
> >> Bug description:
> >>   There seems to be something seriously wrong with either DOLFIN-FFC jit
> >>   compilation or caching or instant.
> >>
> >>   To reproduce, for instance consider the following code snippet and do
> >>   the following
> >>
> >>   (1): Run instant-clean
> >>
> >>   (2): Run script unmodified.
> >>
> >>   Output is:
> >>
> >>   Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>   Calling DOLFIN just-in-time (JIT) compiler, this may take some time.
> >>   Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>   Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>   40.4757877531
> >>
> >>   (3) Uncomment commented lines and run.
> >>
> >>   Output is:
> >>
> >>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>   40.4757877531
> >>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>   40.4757877531 (*)
> >>
> >>   (4) Run instant-clean, comment out lines defining f, g, and 1st print.
> >>   Run.
> >>
> >>   Output is
> >>   Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>   Calling DOLFIN just-in-time (JIT) compiler, this may take some time.
> >>   Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>   Calling FFC just-in-time (JIT) compiler, this may take some time.
> >>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
> >>   40.490263582 (**)
> >>
> >>   Problem: The last two floats, tagged by (*) and (**), should be the
> >>   same: they are not.
> >>
> >>   Code snippet:
> >>
> >>   --
> >>
> >>
> >>   from dolfin import *
> >>   mesh = UnitSquareMesh(16,16)
> >>   V = FunctionSpace(mesh, 'CG', 2)
> >>
> >>   f = Expression("x[0]*x[0] + 2*x[1]*x[1]")
> >>   g = project(f, V)
> >>   print g.vector().norm("l2")
> >>
> >>   #f2 = Expression("x[0]*x[0] + 2*x[1]*x[1]", degree=2)
> >>   #g2 = project(f2, V)
> >>   #print g2.vector().norm("l2")
> >>
> >>
> >>   --
> >>
> >> To manage notifications about this bug go to:
> >> https://bugs.launchpad.net/dolfin/+bug/1153508/+subscriptions
> >>
> >
>
> --
> You received this bug notification because you are a member of DOLFIN
> Core Team, which is subscribed to DOLFIN.
> https://bugs.launchpad.net/bugs/1153508
>
> Title:
>   Strange results in JIT compilation
>
> Status in DOLFIN:
>   Confirmed
>
> Bug description:
>   There seems to be something seriously wrong with either DOLFIN-FFC jit
>   compilation or caching or instant.
>
>   To reproduce, for instance consider the following code snippet and do
>   the following
>
>   (1): Run instant-clean
>
>   (2): Run script unmodified.
>
>   Output is:
>
>   Calling FFC just-in-time (JIT) compiler, this may take some time.
>   Calling DOLFIN just-in-time (JIT) compiler, this may take some time.
>   Calling FFC just-in-time (JIT) compiler, this may take some time.
>   Calling FFC just-in-time (JIT) compiler, this may take some time.
>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
>   40.4757877531
>
>   (3) Uncomment commented lines and run.
>
>   Output is:
>
>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
>   40.4757877531
>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
>   40.4757877531 (*)
>
>   (4) Run instant-clean, comment out lines defining f, g, and 1st print.
>   Run.
>
>   Output is
>   Calling FFC just-in-time (JIT) compiler, this may take some time.
>   Calling DOLFIN just-in-time (JIT) compiler, this may take some time.
>   Calling FFC just-in-time (JIT) compiler, this may take some time.
>   Calling FFC just-in-time (JIT) compiler, this may take some time.
>   Solving linear system of size 1089 x 1089 (PETSc Krylov solver).
>   40.490263582 (**)
>
>   Problem: The last two floats, tagged by (*) and (**), should be the
>   same: they are not.
>
>   Code snippet:
>
>   --
>
>
>   from dolfin import *
>   mesh = UnitSquareMesh(16,16)
>   V = FunctionSpace(mesh, 'CG', 2)
>
>   f = Expression("x[0]*x[0] + 2*x[1]*x[1]")
>   g = project(f, V)
>   print g.vector().norm("l2")
>
>   #f2 = Expression("x[0]*x[0] + 2*x[1]*x[1]", degree=2)
>   #g2 = project(f2, V)
>   #print g2.vector().norm("l2")
>
>
>   --
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/dolfin/+bug/1153508/+subscriptions
>