Programming the HP48 to calculate the cumulative Poisson distribution.

G. Fowler (gof@usna.navy.mil), March 12, 1996.

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Document outline.

Introduction

Programming

Examples

Introduction

The program described in this document computes the cumulative distribution of a Poisson distribution. It creates a function called PCDF. The easiest way to construct this function is to simply write it into the equation editor as one would write it on a piece of paper. Try it on your own or follow the steps in the next section.

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Programming

Read all these directions before programming your calculator!

  1. Press the EQUATION button: Left-shift ENTER.
  2. Type P C D F ( X , L
  3. To insert the closing ) press the right arrow button.
  4. Type = followed by the summation sign which is Right-shift TAN.
  5. Type M=0 followed by the right arrow button, then X and another right arrow button.
  6. Press the "e to the x" button; exponent is -L.
  7. Press the right arrow button to move out of the exponent mode.
  8. Type L and then press the "y to the x power" button; the power is M.
  9. Press the division button. The denominator is M!. The factorial is in the MTH PROB menu.
  10. Press ENTER.
  11. Finally define the function by pressing the DEF button (Left-shift STO).

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Examples

To use this function push X and then L onto the stack. Compute the value of the Poisson CDF by pressing the white button under the menu choice PCDF. You can display the menu with the PCDF choice by pressing the VAR button and the NXT button.

Example 1:

5 ENTER
6 ENTER
PCDF
.76218346

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