Difference between poissrnd and discrete random number (round(rand(1))).

I am using Poissrnd(0.5) and round(rand(1)). Both functions gives discrete random numbers only. But if use poissrnd(0.5) program slow down compared to when I use round(rand(1)). It means program with round(rand(1)) is faster than program with poissrnd(0.5). So I want know any difference between these two functions(according functions wise).

Answer 1

[Roger Stafford]

The two random generators give vastly different results, Murali. The call round(rand) can only give 0 and 1 values which are equally probable, whereas poissrnd(0.5) can give any non-negative integer as a result and these have the characteristic Poisson distribution where the probabilities are certainly not equal. See the Wikipedia site:

 http://en.wikipedia.org/wiki/Poisson_distribution

[murali]

My sense is round(rand(1)*2) can give only 0,1,2 values similarly generate random value with poissrnd(0.5) but I will take only in between 0 and 2. Both computation speed same or not?? In my program if I use poissrnd(0.5) is slow compared to round(rand(1)*2). Just I want to Know is there any big difference according computation speed.