hi all, i am writing some software to model polymerisation kinetics and have created a way of doing so which involves taking ever smaller slices of time to model until some sort of convergence was observed in the results.
so far so good, but i was using 'for i in the range(iterations):' a for loop over each slice of time, where the number of iterations was getting into the tens of millions. up until about 125,000,000 it worked, then i got a MemoryError. now i wasn't surprised to get a memory error eventually because what i was doing was some serous number-crunching. but it didn't occur to me where it was at first. i had to keep some results in memory to calculate something at the end, but that was about a million integers, not that hard with 512 Mb of RAM. then i thought it might be something structural in the way python works, but i couldn't guess at what it might be. thinking about it a bit more, i remembered having read that the for-loop declaration i used actually created a list of integers, which would be eating up over half of my memory before i'd even started doing anything. the program was creating a directory as instructed, then doing nothing, just churning, which made it clear that the problem was encountered right at the start of the program. that helped clear it up, but i was surprised that something as innocuous as the for-loop was creating such a problem. i changed it to a while-loop and it worked fine. has anyone else bumped up against this problem before? i suppose for-loops with 250 million iterations are seldom used in most applications. it was just the first time i'd ever solved a problem by actually having some insight into how python works at a slightly lower level. anyway, sorry to be so long-winded. i'm just glad the damn thing's working again... :) sam -- http://mail.python.org/mailman/listinfo/python-list
