Summary:  Use: random().   Avoid rand(), lrand48().


Random number generating is tricky at best, and it is easy to get bitten.

There are at least 3 different C pseudo random number generating functions:
      rand(), lrand48(), random().

When trying to generate random 0's and 1's with code similar to
            RANDOM %  2
despite seeding the generator with various values, only 4 different 
sequences were obtained.  Actually it is cheaper to use
            RANDOM & 01                                               (A)

Apparently both RANDOM = lrand48(), and RANDOM = rand() have low order bits 
which cycle!  It seems the correct way to generate random bits with 
these functions is
         (int)(2.*RANDOM / (RAND_MAX+1.))                             (B)
which avoids the low order bits.

Better to use RANDOM = random() which does not have the cycling problem. 
Note also that on some systems, initstate() is recommended over srandom().