Hello Alik,

Now “a” does not have upper bound, that’s why on using iterative algorithm with a 
>= 10000 program will stuck on infinite loop because of following line of code:
double b = pow(2.0, s - 1.0);
Because after overflow “b” becomes “+Inf”.

Yep, overflow can happen.

So should upper bound for “a" be set?

Yes, I agree. a >= 10000 does not make much sense... If you want uniform you should use random(), not call random_zipfian with a = 10000. Basically it suggests that too large values of "a" should be rejected. Not sure where to put the limit, though.

Should I mention in docs that there are two algorithms are used depending on values of a(s/theta)?

Yes, as a general principle I think that the documentation should reflect the implementation.

In attaching patch, I have added computeIterativeZipfian method and it’s usage in getZipfianRand. Is it better to move code of computing via cache to new method, so that getZipfianRand will contain only 2 computeXXXZipfian method calls?

I have not looked in detail, but from what you say I would agree that the implementation should be symmetric, so having one function calling one method or the other sounds good.

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