# Re: Random number generators

*From*: frank <frank@xxxxxxxxxxxxxxx>*Date*: 17 Nov 2009 02:04:44 GMT

On Mon, 16 Nov 2009 16:05:14 -0800, steve wrote:

I have a question regarding the subroutine RANDOM_NUMBER, does it

generate a list of uniformly distributed numbers, between 0 and 1, and

an average of 0.5?

The description for RANDOM_NUMBER is given in 13.14.85 of the Fortran 95

standard. It states

Description. Returns one pseudorandom number or an array of

pseudorandom numbers from the uniform distribution over the range 0

<= x < 1.

Note, it says nothing about an average of 0.5. If you only draw 2

values from the distribution is highly unlikely that the average is 0.5.

OTOH, if you draw hundred or thousands or millions of samples, then

the average will be near 0.5.

Isn't there an asymmetry in the unit interval though as to which endpoint

is included? So if there's N outcomes on one side of .5 there would be N

+-1 on the other.

--

frank

"Guns: yes, they are harmful."

.

**Follow-Ups**:**Re: Random number generators***From:*Ron Shepard

**Re: Random number generators***From:*steve

**References**:**Random number generators***From:*Marina

**Re: Random number generators***From:*steve

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