[Users] McLachlan test suite

[Ian Hinder]

Hi all,

I have written some test cases for the McLachlan evolution code.  This  
thorn is currently used in other test suites, but it doesn't have one  
of its own.  The minimal test I have written is a 3D diagonal gauge  
wave in unigrid with periodic boundary conditions run for one crossing  
time, so mostly it tests that the RHSs are correct.  There are two  
resolutions (15^3 and 30^3) as well as the exact solution as computed  
by Exact, so from the test suite output you can compute convergence to  
test that everything is correct (the automatic regression testsuite  
mechanism does not do this though).  I attach the parameter files for  
comments.  I have tested 4th order convergence to the exact solution.

I have enabled 3D HDF5 output in the test suite in anticipation that  
we might want to have HDF5 comparisons added at some point, and so  
that when investigating failures there is full information available.   
The output is from the initial data and the last iteration only, with  
full compression.

The test output sizes are:

n = 15		2.9 M
n = 30		7.9 M
Exact		100 kB

Total: 11 M

For the exact solution I only output 3D of the admbase gxx and kxx  
variables.  If this is considered too large, we can omit the 3D HDF5  
output for now, as it is not used in the current Cactus testsuite  
mechanism.

I have put the test suites in the existing ML_BSSN_Helper thorn, as  
this seemed the easiest solution, since ML_BSSN is automatically  
generated.

The test does not test the shift terms.  For that I would use the  
shifted gauge wave solution, but as far as I know the harmonic shift  
gauge condition is not implemented in McLachlan.

The tests are run on 2 processes as CarpetIOASCII output is used, so  
the output depends on the number of processes.  If output on 1 process  
is better, let me know.  In principle, the number of OpenMP threads  
should not matter in this case.  However, the tests seem to fail if I  
use OMP_NUM_THREADS=2 (or leave it unset on my dual-core laptop, which  
makes it use 2).  The failure is:

  Issuing mpirun -np 2 /Users/ian/Cactus/llama/exe/cactus_mcl /Users/ 
ian/Cactus/llama/arrangements/McLachlan/ML_BSSN_Helper/test/ 
gw3d_Exact_ord4_15.par

   alp.norm1.asc: differences below tolerance on 1 lines
   alp.norm2.asc: differences below tolerance on 1 lines
   alp.sum.asc: substantial differences
      significant differences on 1 (out of 2) lines
      maximum absolute difference in column 3 is 1.00044417195022e-11
      maximum relative difference in column 3 is 2.96613722781153e-15

  Failure: 12 files compared, 3 differ, 1 differ significantly

  Files which differ strongly:
    [1] alp.sum.asc

I don't know why this fails.

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