[Dune] Re: Was genau ist..

[Christian Engwer]

> Error: Quadrature for (simplex, 3) and order=4 does not sum to volume of
> RefElem
> Sums to 0.166667( RefElem.volume() = 0.166667)(difference 3.33333e-10)
> Error: Quadrature for (simplex, 3) and order=5 does not sum to volume of
> RefElem
> Sums to 0.166667( RefElem.volume() = 0.166667)(difference 3.33333e-10)
> Error: Quadrature for (simplex, 3) and order=5 does not sum to volume of
> RefElem
> Sums to 0.166667( RefElem.volume() = 0.166667)(difference 3.33333e-10)

> 3.3e-10 ist doch ok.

This test integrates the 1 over the reference element. To me it seems
like there is typo in the weights of this rule, because usually we
have an error of order of 1e-14/1e-15.

Also if this quadrature rule is so bad, I would consider this a bug,
because we promise to integrate functions up to the order of our rule
exactly. Exactly for a computer means that you create no error greater
then the error introduced through the finite accuracy of your floating
point numbers. This means that 3e-10 is far to big.

Christian