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SigmaPSN - Sum of Poisson Distribution

Overview

This calculates the sum of Poisson distribution,
Sum(n=0..N0)P(mu,n)
= exp(-mu)[1 + mu/1 [1 + mu/2 [1 + mu/3[ .... [1 + mu/N0]....]]]]

Input variables

mu : expected value
N0 : upper limit of n (0 or positive integer)

Stack/Registers/Flags

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

No flags are used.

Registers

R00 : current n

Usage

	XEQ "SigmaPSN"
	enter mu and N0
	R/S
		... shows the sum
			

Program

V1.00 February 12, 2007

    00   { 60-Byte Prgm }        ;
    01 LBL "SigmaPSN"            ; Sigma=ALPHA down MATH Sigma
    02   MVAR "mu"               ; mu = ALPHA down MATH mu
    03   MVAR "N0"               ;
    04   VARMENU "SigmaPSN"      ;
    05   STOP                    ;
    06   EXITALL                 ;
    07   1                       ;
    08   STO 00                  ; avoid divide by 0 if N0==0
    09   RCL "N0"                ;
    10   X=0?                    ;
    11   GTO 02                  ; if N0==0, 0 is kept in x
    12   STO 00                  ; else R00=N0
    13   1                       ;     x = 1
    14 LBL 02                    ;
    15   RCLx "mu"               ; multiply the current x
    16   RCL/ 00                 ;
    17   1                       ;
    18   +                       ;
    19   DSE 00                  ;
    20   GTO 02                  ;
    21   RCL "mu"                ; multiply e^-mu
    22   +/-                     ;
    23   E^X                     ;
    24   x                       ;
    25   .END.                   ;
			

Programmed by Taku Yamanaka, February 12, 2007.