Am 07.11.2012 21:42, schrieb Allin Cottrell:
On Wed, 7 Nov 2012, Pindar wrote:


Indeed, on my W7 PC with the new snapshot the 'evals' are 
not the same. The order within the bins is different. I 
expected the null operation and checked other parts of the 
code until I found the reason explained. I gonna try with 
'matrix K' instead of the ~ operation and report then.

OK, I suspect this must be a difference between the 
implementation of the qsort() function in the Microsoft C 
library and the GNU C library. The C standard doesn't specify 
whether or not elements of an array passed to qsort() that 
compare equal will remain in the original order. Apparently 
glibc is preserving the original order while MS is messing 
with it.
Printing test gives:

-8    0 \  16    0 \  -6    0 \   2    0\  -4    0 \   0    0 \   0    0 \   0    0 \   0    0 \
   0    0 \   0    0 \   0    0 \   0    0 \   0    0 \   0    0 \   0    0 \   0    0 \   0    0 \
   8    0 \  -3    0 \   8    0 \  -8    0 \  -6    0\   1    0

Here the rearrangement happens in the first and last bin.
I gonna change my script in that way that I make the assumption that the dataset is always sorted according to FactorA.
I think that should be fine.
In many contexts I guess this won't make any relevant 
difference, but in some contexts it can. If it's important to 
avoid reordering of elements that compare equal we can use a 
fancier comparison function that looks at the addresses of the 
elements when the values compare equal.

Allin Cottrell
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