ffc team mailing list archive

[Kristian Oelgaard <k.b.oelgaard@xxxxxxxxxx>]

Quoting Anders Logg <logg@xxxxxxxxx>:

> On Tue, Mar 18, 2008 at 02:37:49PM -0400, Marie Rognes wrote:
> > Kristian Oelgaard wrote:
> > > Quoting Marie Rognes <meg@xxxxxxxxxxx>:
> > >
> > >   
> > >>
> > >> However, this time it is actually not simplify that is the main
> culprit:
> > >>
> > >>     After index reassignment:
> > >>      
> > >>           0.5 | vi0[0]*vi1[0]*dX(0) + 0.5 | vi0[0]*vi1[0]*dX(0) + 0.5 |
> > >>     vi0[1]*vi1[1]*dX(0) + 0.5 | vi0[1]*vi1[2]*dX(0) + 0.5 |
> > >>     vi0[2]*vi1[2]*dX(0) + 0.5 | vi0[2]*vi1[1]*dX(0) + 0.5 |
> > >>     vi0[3]*vi1[3]*dX(0) + 0.5 | vi0[3]*vi1[3]*dX(0)
> > >>      
> > >>       After simplification:
> > >>      
> > >>           0.5 | vi0[b0]*vi1[b0]*dX(0) + 0.5 | vi0[b0]*vi1[b0]*dX(0) +
> > >>     0.5 | vi0[1]*vi1[2]*dX(0) + 0.5 | vi0[2]*vi1[1]*dX(0)
> > >>
> > >>
> > >> where the index b0 has range [0, 1, 2, 3] in the first term and [0, 3] 
> > >> in the second term. This makes sense.
> > >>     
> > >
> > > Maybe, on a side note: the fact that 'b0' can have a different range in
> each
> > > monomial makes it pretty difficult to debug/understand what is going on
> by just
> > > looking at the pretty print version of the form. The index should be
> different
> > > in my opinion.
> > >
> > >   
> > 
> > Agree. Maybe we could have two versions of printing indices, one with 
> > the ranges (if set) ala
> > 
> >     b0 (0, 1, 2, 3)
> > 
> > for debug purposes and a denser one for non-debug purposes?
> > 
> > Actually, that would be a starting point for an accurate factorization 
> > check too.
> 
> See if it works now. It was a simple fix (assuming it works) to
> include the index range in the computation of signatures (see
> signature.py).

Yes, it works, but the output could be optimised:

    // Compute geometry tensors
    const double G0_ = det;
    const double G1_ = det;
    const double G2_ = det;
    const double G3_ = det;
    
    // Compute element tensor
    A[0] = 0.25*G0_ + 0.25*G1_;
    A[1] = 0;
    A[2] = 0;
    A[3] = 0;
    A[4] = 0;
    A[5] = 0.25*G0_;
    A[6] = 0.25*G2_;
    A[7] = 0;
    A[8] = 0;
    A[9] = 0.25*G3_;
    A[10] = 0.25*G0_;
    A[11] = 0;
    A[12] = 0;
    A[13] = 0;
    A[14] = 0;
    A[15] = 0.25*G0_ + 0.25*G1_;

So something in factorization should change.

And it would be nice to include some information about the range of the indices
in the form signature:

  After simplification:

      0.5 | vi0[b0]*vi1[b0]*dX(0) + 0.5 | vi0[b0]*vi1[b0]*dX(0) + 0.5 |
vi0[1]*vi1[2]*dX(0) + 0.5 | vi0[2]*vi1[1]*dX(0)

b0 in first product 0-3, in second 0-1.

Kristian



> 
> -- 
> Anders
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