dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

Can you make it even smaller? And make it build against the current
development version?

/Anders


On Wed, Oct 04, 2006 at 04:08:31PM +0200, Dag Lindbo wrote:
> The code I attach breaks the function. Should be very simple to make, and
> understand. main() is in LSM_test.cpp
> 
> /Dag
> 
> >
> > It will take me some time to write a stand-alone code that someone else
> > can run, so hang on.
> >
> > Gdb says:
> >
> > Program received signal SIGSEGV, Segmentation fault.
> > [Switching to Thread -1208269120 (LWP 12715)]
> > 0x004776ed in dolfin::DiscreteFunction::updateVectorDimension ()
> >    from /usr/local/lib/libdolfin.so.0
> >
> >
> > Valgrind says the same (I guess):
> >
> > ==12683== Invalid read of size 4
> > ==12683==    at 0x1BA106EA:
> > dolfin::DiscreteFunction::updateVectorDimension() (in
> > /usr/local/lib/libdolfin.so.0.0.0)
> > ==12683==    by 0x1BA10966:
> > dolfin::DiscreteFunction::DiscreteFunction(dolfin::uBlasVector&,
> > dolfin::Mesh&, dolfin::FiniteElement&) (in
> > /usr/local/lib/libdolfin.so.0.0.0)
> > ==12683==    by 0x1BA13B30:
> > dolfin::Function::Function(dolfin::uBlasVector&, dolfin::Mesh&,
> > dolfin::FiniteElement&) (in /usr/local/lib/libdolfin.so.0.0.0)
> > ==12683==    by 0x804E1FB:
> > dolfin::Vec_Func_fcns::L2_Error_DF_DF(dolfin::Mesh&, dolfin::Function&,
> > dolfin::Function&) (Vec_Func_fcns.cpp:41)
> > ==12683==    by 0x808F6E6: main (LSM_test.cpp:135)
> > ==12683==  Address 0x1BD79D68 is 0 bytes inside a block of size 12 free'd
> > ==12683==    at 0x1B9098CF: operator delete(void*)
> > (vg_replace_malloc.c:155)
> > ==12683==    by 0x804F87D:
> > dolfin::Scalar_L2Error::LinearForm::FunctionElement_1::~FunctionElement_1()
> > (Scalar_L2Error.h:228)
> > ==12683==    by 0x1BA0D703: dolfin::Form::~Form() (in
> > /usr/local/lib/libdolfin.so.0.0.0)
> > ==12683==    by 0x1BA0FBCA: dolfin::LinearForm::~LinearForm() (in
> > /usr/local/lib/libdolfin.so.0.0.0)
> > ==12683==    by 0x80539FF:
> > dolfin::Scalar_L2Error::LinearForm::~LinearForm() (Scalar_L2Error.h:23)
> > ==12683==    by 0x804E52B:
> > dolfin::Vec_Func_fcns::L2_Error_Exact(dolfin::Mesh&, dolfin::Function&,
> > dolfin::Function&) (Vec_Func_fcns.cpp:29)
> > ==12683==    by 0x808F666: main (LSM_test.cpp:131)
> > pure virtual method called
> > terminate called without an active exception
> >
> >
> >
> >> On Sun, Oct 01, 2006 at 06:35:51PM +0200, Dag Lindbo wrote:
> >>> Hi all,
> >>>
> >>> I'm a bit confused about passing a Function to a function and using it
> >>> to
> >>> assemble some system. What I'm doing is passing a Function, "func", by
> >>> reference, to a function, foo, where func goes into a form and that
> >>> form
> >>> is assembled etc.
> >>>
> >>> Vector& Another_Class::foo(Mesh& mesh, Function& func)
> >>> 	{
> >>> 		AAA::BilineraForm a
> >>> 		AAA::LinearForm L(func)
> >>>
> >>> 		FEM:assemble(...)
> >>> 		lu_solver.solve(...)
> >>>
> >>> 		return x;
> >>> 	}
> >>>
> >>> This works fine, but when the context that called foo (e.g. main)
> >>> resumes
> >>> something has happended to "func". The next time it is referenced the
> >>> porgram terminates with a segmentation violation. To get around this I
> >>> can
> >>> copy the data to local Vector in foo:
> >>>
> >>> Vector& Another_Class::foo(Mesh& mesh, Function& func)
> >>> 	{
> >>> 		Vector vec = func.vector();
> >>> 		Function func2(vec,mesh,func.element());
> >>>
> >>> 		AAA::BilineraForm a
> >>> 		AAA::LinearForm L(func2)
> >>>
> >>> 		FEM:assemble(...)
> >>> 		lu_solver.solve(...)
> >>>
> >>> 		return x;
> >>> 	}
> >>>
> >>> I would dearly like to avoid this extra copy of a large vector. How
> >>> should
> >>> one do this?
> >>>
> >>> Regards,
> >>> Dag Lindbo
> >>
> >> This should not happen so it looks like a bug. Passing a function as
> >> argument to a form only has the effect that the pointer to the
> >> function is placed in a list. During assembly, all functions in the
> >> list will be interpolated to each element. The pointer is never
> >> deleted.
> >>
> >> See if you can produce a simplest possible example that breaks and
> >> maybe we can find out what goes wrong. Also check with valgrind if you
> >> have it availabe and see if you can locate the offending line.
> >>
> >> /Anders
> >> _______________________________________________
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> >> http://www.fenics.org/mailman/listinfo/dolfin-dev
> >>
> >
> >
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> >


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