Thread Subject: normally distributed random integers

Hi.
I'm trying to find a way to generate a set of random integers with a given mean and standard deviation, much like the randn function (except the randn function generates floats). Any ideas?

"Anders Stephansen" <aswsw@start.no> wrote in message <h7qp9b$mt4$1@fred.mathworks.com>...
> Hi.
> I'm trying to find a way to generate a set of random integers with a given mean and standard deviation, much like the randn function (except the randn function generates floats). Any ideas?

They won't be normally distributed if they are integers.
By definition of the normal distribution, they won't
be normal, since it is continuous.

So why not use randn, and then just round them?
(This may introduce a small bias into the mean.)

John

> I'm trying to find a way to generate a set of random integers with a given mean and standard deviation, much like the randn function (except the randn function generates floats). Any ideas?

something like:
scale = 10;
bias = 5;
N = 100;
int_gauss = round(scale*randn(N,1)+bias);

"Anders Stephansen" <aswsw@start.no> wrote in message <h7qp9b$mt4$1@fred.mathworks.com>...
> Hi.
> I'm trying to find a way to generate a set of random integers with a given mean and standard deviation, much like the randn function (except the randn function generates floats). Any ideas?

You might take a look at Poisson's pdf which converges toward a normal pdf when lambda parameter goes to infinity (select a large one is OK):

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

Bruno

"John D'Errico" <woodchips@rochester.rr.com> wrote in message <h7qqru$hf9$1@fred.mathworks.com>...
>
> They won't be normally distributed if they are integers.
> By definition of the normal distribution, they won't
> be normal, since it is continuous.
>
> So why not use randn, and then just round them?
> (This may introduce a small bias into the mean.)
>
> John

Oh, sorry. They don't to be normal, they just need to have a given standard deviation and mean. Seems like a rounded randn set works fine.