[Users] McLachlan constraint time levels

Bruno C. Mundim bcmsma at astro.rit.edu
Wed Feb 9 23:19:52 CST 2011

Ok, that seems fair enough, but shouldn't we then tag those groups with 
"prolongation=none"? that would avoid the warning messages when looking 
at 3D output. What do you think?


Erik Schnetter wrote:
> Bruno
> This depends on whether you want the mesh refinement boundaries of the
> constraint variables be interpolated from the next coarser grid, or
> remain undefined/set to zero. In principle, these boundaries are not
> important if you are looking for 3D output, but if you want to look at
> reductions then you will need time interpolation. However, this
> requires in addition that the constraints be calculated at every
> iteration, and is thus expensive both in terms of memory requirements
> and computing time requirements. Most people are therefore fine with
> undefined prolongation boundaries and only look at e.g. 1D output,
> ignoring the ghost and boundary points.
> -erik
> On Wed, Feb 9, 2011 at 5:34 PM, Bruno Coutinho Mundim
> <bcmsma at astro.rit.edu> wrote:
>> Hi,
>> I am receiving the messages of the following kind in my simulation with
>> McLachlan:
>> (line 1084 of ./Cactus/arrangements/Carpet/CarpetReduce/src/reduce.cc):
>>   -> Grid function "ML_BSSN::H" has only 1 time levels on refinement
>> level 0; this is not enough for time interpolation
>> and it is indeed true that the constraint variables has 1 time level only:
>> CTK_REAL ML_Ham type=GF timelevels=1 tags='tensortypealias="Scalar"
>> tensorweight=0'
>> {
>>   H
>> } "ML_Ham"
>> I was wondering if we shouldn't be using 3 time levels instead.
>> Thanks,
>> Bruno.
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