V110 Poisson Random Numbers

OBSOLETE

Please note that this routine has been obsoleted in CNL 218. Users are advised not to use it any longer and to replace it in older programs. No maintenance for it will take place and it will eventually disappear.
Suggested replacement: RNPSSN (V136)

POISSN generates a random integer N according to a Poisson law:

$Prob(N)\; =\; \{1N!\}\hspace{0.17em}e-\mu \mu N,$

where $\mu >\; 0$ (the mean) is a constant specified by the user.

Structure:

SUBROUTINE subprogram
User Entry Names: POISSN, POISET
External References: RANNOR (V100), RNDM (V104)

Usage:

    CALL POISSN(AMU,N,IERR)

AMU

Mean $\mu$ .

N

The generated random number, Poisson distributed, with mean AMU.

IERR

Error flag.
$=\; 0:$ Normal case.
$=\; 1:$ $AMU\; \le 0$ .

    CALL POISET(AMAX)

Timing:

In $\mu$ sec per call:

Los Alamos report LA-5061-MS
$•$

V111