Intolerable differences have not been found. They are always minor <%5 and their source can come from several places. For example, different compilers (or even different versions of the same compiler) can have different sorting behavior when presented with objects that have equivalent comparators. Others occur with data structures being written/read to disk (Im still trying to fully understand those). As well as a host of other potential differences as you mention below.
However, no cases have been found to fall outside expected and accepted tolerance levels.
-Zeke
On 20 February 2016 at 17:28, Bruce Fischl fischl@nmr.mgh.harvard.edu wrote:
hmmm, the only thing that worries me about dynamic linking is that it will add variability to the outputs. Zeke has spent endless amounts of time tracking down e.g. mac vs. pc differences in math libs and such.
What sort of differences were found? Differences in transcendental functions are to be expected (so long as they are small) and lots of other things can cause slightly different results to be generated from floating point calculations (for instance, when summing an array, the result might vary with the number of OpenMP threads used). Were the segmentations produced intolerably different?
Regards,
Richard _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer