Functions and CALL Routines 
Returns a random variate from a Poisson distribution.
Category: 
Random Number

Tip: 
If you want to change the seed value during execution,
you must use the CALL RANPOI routine instead of the RANPOI function.


seed

is a numeric constant, variable, or expression
with an integer value. If seed 0, the time of day is used
to initialize the seed stream.
Range: 
seed <
2^{31}1 
See: 
Seed Values for more information about seed
values 

m

is a numeric constant, variable, or expression
that specifies the mean of the distribution.
Range: 
m 0 
The RANPOI function returns a variate
that is generated from a Poisson distribution with mean m.
For m < 85, an inverse transform method applied
to a RANUNI uniform variate is used (Fishman 1976) (See References). For m 85, the normal approximation
of a Poisson random variable
is used. To expedite execution, internal variables are calculated only on
initial calls (that is, with each new m).
For a discussion about seeds and streams of data, as well as examples
of using the randomnumber functions, see Generating Multiple Variables from One Seed in RandomNumber Functions.
The CALL RANPOI routine, an alternative to the RANPOI function,
gives greater control of the seed and random number streams.
Functions and CALL routines:
Copyright © 2011 by SAS Institute Inc., Cary, NC, USA. All rights reserved.