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PSN - Poisson Distribution

Overview

Calculates the Poisson Distribution,
P(mu,n) = e^-mu mu^n / n!

Input variables

mu : expected value
N : the number of observed events

Stacks/Registers/Flags

The contents of x, y, z and t registers are destroyed.

No registers and flags are used.

Usage

	XEQ "PSN"
	enter mu and N
	R/S
		... displays P(mu,N).
			

Program

V1.00 11-Oct-1990

    00    { 36-Byte Prgm }
    01  LBL "PSN"             ;
    02    MVAR "mu"           ; mu = ALPHA down MATH mu
    03    MVAR "N"            ;
    04    VARMENU "PSN"       ;
    05    STOP                ;
    06    EXITALL             ;
    07    RCL "mu"            ;
    08    ENTER               ;
    09    +/-                 ;
    10    E^X                 ;
    11    X<>Y                  ; x=mu y=exp(-mu)
    12    RCL "N"             ;
    13    Y^X                 ; mu^n
    14    LASTX               ; n
    15    N!                  ;
    16    /                   ;
    17    x                   ;
    18    .END.               ;
			

Programmed by Taku Yamanaka, October 11, 1990.