Hi,
I've noticed this difference too. But I think I'm too much of a
Fortran sceptic! A long time ago, I went through the Modelfree4
source code with a fine toothed comb and found 4 bugs in there. A few
of these were code issues which had no effect on the Portland compiler
(well the compilation part anyway) but was causing gcc to complain
loudly. Rightfully so as there was an undeclared variable used as a
counter in a loop - it's value was garbage. One of the bugs was a
problem with the Levenberg-Marquardt algorithm and that, together with
the other problems found in:
d'Auvergne, E. J. and Gooley, P. R. (2008). Optimisation of NMR
dynamic models I. Minimisation algorithms and their performance within
the model-free and Brownian rotational diffusion spaces. J. Biomol.
NMR, 40(2), 107-119. (http://dx.doi.org/10.1007/s10858-007-9214-2)
was the reason for Modelfree 4.20 to be released. The other bugs
caught by gcc, and the undeclared variable were the reason for
Modelfree 4.16
(http://cpmcnet.columbia.edu/dept/gsas/biochem/labs/palmer/software/modelfree.html).
So I'm not sure if the speed of the two binaries is the best measure
of quality. It could be that the Portland version is faster due to a
bug. Or that the gcc one is slower due to higher precision. Who
knows?
I'm not sure how we could advise the user. Maybe a print out at the
start of palmer.execute()? I think it would be best to advise the
user to only use Modelfree4 as a test and that it should be compared
to the much higher precision - hence slower - relax results. It might
also be worth stating that the Portland and gcc versions give
different results. Eg in the system test I created for it, one finds
the diffusion tensors:
gcc:
tm = 8.964
Dratio = 1.324
theta = -52.070
phi = 2.377
Portland:
tm = 8.443
Dratio = 1.053
theta = 68.864
phi = 73.913
There is no glide or reflection symmetry here, so the results are
quite different.
Regards,
Edward
Re: r7704 - /1.3/test_suite/system_tests/palmer.py