Anna Sidera <sidera.anna@xxxxxxxxx> writes: > The program I wrote uses 2*10^8 random numbers which are produced using rand. Is there a way to find if rand produces duplicates in my program? I found that RAND_MAX is equal to 2^31-1 in the machine I am using. This question doesn't have anything to do with gcc. This is the wrong mailing list. Please take this discussion to some other list. Thanks. If duplicates are important, why not just collect the numbers and check? It seems to me that a high quality random number generator would likely produce a couple of duplicates in such a long sequence. But I know little about random number generation. Ian > ----- Original Message ----- > From: Ian Lance Taylor <iant@xxxxxxxxxx> > Date: Saturday, August 6, 2011 10:01 pm > Subject: Re: question on rand() > >> Anna Sidera <sidera.anna@xxxxxxxxx> writes: >> >> >>From this, can I find out when the numbers start repeating? How >> can I find it? I cannot find the period using >> > >> > man rand >> >> This question really doesn't have anything to do with gcc. gcc >> does not >> provide a rand function. The rand function will come from your C >> library, and gcc does not include a C library. >> >> If you are using GNU glibc, which is probably the case if you are >> usinga GNU/Linux system, then rand is not implemented as a linear >> congruential generator, and the period is quite long. See the source >> code. >> >> Ian >>
