[Users] Meeting minutes

[Ian Hinder]

On 24 May 2011, at 17:50, Erik Schnetter wrote:

> On Tue, May 24, 2011 at 2:11 AM, Ian Hinder <ian.hinder at aei.mpg.de> wrote:
>> 
>> On 23 May 2011, at 23:49, Bruno Coutinho Mundim wrote:
>> 
>>> 
>>>> * Bruno still has troubles with RotatingSymmetry180 when using the
>>>> development version of ET for the BBH example (parfile is in subversion)
>>>> * will try running without RotatingSymmetry180
>>> 
>>> Just got the results: no problem without RotatingSymmetry180.
>> 
>> OK good, so we know where the problem is.
>> 
>>> 
>>>> * convergence in norms is bad, somewhat better in 1D data for a short
>>>> time after simulation startup
>>> 
>>> A closer look into the initial data revealed that both the l2-norm of
>>> the hamiltonian constraint and its value along the x-axis converge to
>>> the expected order, 4th order. This convergence is not observed anymore
>>> in the very next coarse step when the comparison is done again.
>> 
>> The time prolongation is only 3rd order accurate so I wouldn't expect convergence at 4th order.
> 
> Time prolongation is second order accurate.

As I understand it, the three-point interpolation (from the three timelevels) is locally 3rd order accurate, but when you add up T/dt of them to get to a fixed time, you reduce the order to 2.  I tend to get confused about this, but do we agree on this?

-- 
Ian Hinder
ian.hinder at aei.mpg.de