fenics team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Jed Brown wrote:
> On Sat 2008-06-07 19:40, Anders Logg wrote:
> > On Sat, Jun 07, 2008 at 09:17:03AM -0700, Chong Luo wrote:
> > > What is the default precision of FEniCS, is it double precision or single
> > > precision?
> > >
> > > I have this question, because for exact solution in P(2), using P(2) element
> > > gave me an error of order 1E-7 instead of 1E-14.
> > It doesn't work that way (unfortunately). The error depends on the
> > mesh size. Or did you refine until convergence?
>
> If the exact solution is really in P_2 then it can be represented exactly in the
> finite element space.  Is it possible that the quadrature rule was inexact in
> this case?  

Yes, because FFC writes C++ code with finite precision. It can be 
controlled through an FFC flag (or at least it used to be).

Garth

If an iterative method was used, were the tolerances cranked way up?
> Jed
>
>
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