hi mike, i've been writing down everything i know about random numbers with C. thanks for the info! i hope to have something useful in a day or so.
begin [EMAIL PROTECTED] <[EMAIL PROTECTED]> > > Sometimes is very valuable to be able to have pseudo-random numbers > which can re-generate a certain sequence of numbers: this is because if > your program uses "rand" and crashes sometimes, you can set the seed > value to some constant number that you know leads to a crash then rerun > a few times with gdb to figure out what is going wrong... i was able to track down an "off by one" error in my code using this technique a few weeks ago. it was non-fatal, and i had no idea where the bad numbers were coming from. saving the seed was VERY useful. > As I said to Mark last time stuff about rand/random came up. If > you want lots of non-reproducible random numbers you should open > up the /dev/urandom device and read bytes from there... from read to > read you will get randomized stuff. If you are doing something > cryptographically sensitive then open /dev/random, but don't try to > read much data from that device it will block readers until it > has enough "collected entropy"... i remember, but reading a file is fine for setting a seed (that's what i do) but for generating a random number, it can be unsuitable. a monte carlo simulation needs between 100,000 and 100,000,000 random numbers. reading a file for all those numbers would be prohibitive. pete _______________________________________________ vox-tech mailing list [EMAIL PROTECTED] http://lists.lugod.org/mailman/listinfo/vox-tech
