dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

Great. We'll be upgrading to PETSc 2.3 as soon as I get the chance.

/Anders

On Tue, Jun 14, 2005 at 03:47:10PM -0500, Barry Smith wrote:
> 
>   This is not correct.
> 
>   Regardless, with PETSc 2.3 and higher you do not need to provide this
> flag. PETSc itself keeps track of whether the extern "C" is needed or not.
> 
>    Barry
> 
> 
> On Tue, 14 Jun 2005, Matthew Knepley wrote:
> 
> > Anders Logg <logg@xxxxxxxxx> writes:
> > 
> >        This flag says:
> > 
> >   1) You configured with --with-clanguage=C++ so that the C++ compiler is used to
> >      compile the libraries.
> > 
> >   2) The PETSc symbols are NOT mangled when using PETSC_USE_EXTERN_CXX so C code
> >      can call these symbols.
> > 
> > This is not are normal mode. We believe if you want to compile with C++, then you
> > want mangled symbols.
> > 
> >      Thanks,
> > 
> >         Matt
> > 
> > > I think we added a
> > >
> > > PETSC_CFLAGS="$PETSC_CFLAGS -DPETSC_USE_EXTERN_CXX"
> > >
> > > just below the definition of PETSC_CFLAGS in configure.ac.  You need
> > > to add this, then run scripts/preconfigure and then ./configure again.
> > >
> > > We get PETSC_CFLAGS by
> > >
> > > PETSC_CFLAGS=`make -s -C $PETSC_DIR getincludedirs PETSC_DIR=$PETSC_DIR BOPT=$BOPT`
> > >
> > > which I think should be enough. I don't know why the extra
> > > -DPETSC_USE_EXTERN_CXX helps on some systems or why it's not included
> > > with getincludedirs.
> > >
> > > /Anders
> > >
> > > On Tue, Jun 14, 2005 at 01:38:05PM -0500, Andy Ray Terrel wrote:
> > >> Sorry to bother you again.  But when I tried to run some things with 
> > >> dolfin I just got a PETSc Error.  So I tried to rebuild but remembered 
> > >> that when I built the first time I had to add some linker to PETSc 
> > >> somewhere.  Well I have forgotten what it was we added to get PETSc to 
> > >> link.  Do you remember?
> > >> 
> > >> Andy
> > >> 
> > >> Anders Logg wrote:
> > >> 
> > >> >You need to do A and B separately, as two different forms in two
> > >> >different files.
> > >> >
> > >> >In the first file, do something like
> > >> >
> > >> >   vector = FiniteElement("Vector Lagrange", "triangle", 1)
> > >> >
> > >> >   v = BasisFunction(vector)
> > >> >   u = BasisFunction(vector)
> > >> >
> > >> >   a = v.dx(i)*u.dx(i)*dx
> > >> >
> > >> >In the second file, do something like
> > >> >
> > >> >   vector = FiniteElement("Vector Lagrange", "triangle", 1)
> > >> >   scalar = FiniteElement("Lagrange", "triangle", 1)
> > >> >   
> > >> >   q = BasisFunction(scalar)
> > >> >   u = BasisFunction(vector)
> > >> >
> > >> >   a = q*u[i].dx(i)*dx
> > >> >
> > >> >Compile each form and then assemble separately in DOLFIN to get A and B.
> > >> >You can then either combine A and B to get the full matrix, or you can
> > >> >do fixed-point iteration, or you can create something called a
> > >> >"VirtualMatrix" in DOLFIN which implements the matrix-vector product
> > >> >for the full matrix in terms of A and B.
> > >> >
> > >> >Hope this helps. Ask me again when you need more help.
> > >> >
> > >> >/Anders
> > >> >
> > >> >On Tue, Jun 14, 2005 at 09:48:43AM -0500, Andy Terrel wrote:
> > >> > 
> > >> >
> > >> >>Hey Anders,
> > >> >>
> > >> >>I am having some trouble figuring out how to write some stokes equations 
> > >> >>up for my project.  So I have the forms:
> > >> >>
> > >> >>a = v.dx(j) *u.dy(j)
> > >> >>b= q*r*dx
> > >> >>
> > >> >>and I want to construct the matrix C s.t.
> > >> >>   [ A   B^t  ]
> > >> >>C=[ B    0     ]
> > >> >>
> > >> >>This is so I can call some mixed methods for the solving of the problem 
> > >> >>to get the benchmarking results.
> > >> >>
> > >> >>If you have time can you help me?
> > >> >>
> > >> >>Andy
> > >> >>
> > >> >>PS This is to solve (grad(u), grad(v)) - (p, div(v)) = 0,
> > >> >>                           (div(u), w) = 0.
> > >> >>
> > >> >>   
> > >> >>
> > >> >
> > >> > 
> > >> >
> > >> 
> > >
> > >
> > >
> > >
> > 
> > 
> 
> _______________________________________________
> DOLFIN-dev mailing list
> DOLFIN-dev@xxxxxxxxxx
> http://www.fenics.org/cgi-bin/mailman/listinfo/dolfin-dev
> 

-- 
Anders Logg
Research Assistant Professor
Toyota Technological Institute at Chicago
http://www.tti-c.org/logg/