Britton,
Here's the output after adding the patch and choosing the process with the issue: before cleaning dic 10000 dicri 10000 count1 3794 count2+count3 3794
It didn't print "Real index -1!!!" or "Padded index -1!!!"? Did you notice the other 'self.mine == -1'? The reason I ask, is because of the counts, it looks like the same number of elements are being added to self.dic and self.dicri. But when the array is cleaned up, the two have different lengths, which my first guess was that there was a particle_index == -1 that was being added. Let me think about this some more... _______________________________________________________ sskory@physics.ucsd.edu o__ Stephen Skory http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student ________________________________(_)_\(_)_______________