(HP65) Factorial and Gamma Function
10-21-2017, 08:32 AM (This post was last modified: 10-26-2017 05:10 AM by Gamo.)
Post: #1
 Gamo Senior Member Posts: 471 Joined: Dec 2016
(HP65) Factorial and Gamma Function
Just noticed that HP 65 cannot calculate decimal Factorial and HP67 app for Android also cannot do it.

Here is a handy program using Stirling's approximation for Factorial and Gamma Function.

This approximation is good for x<70

Program:

Code:
 LBL A 571 ENTER 2488320 / CHS STO 1 139 ENTER 51840 / CHS STO 2 288 1/x STO 3 12 1/x STO 4 CLx RTN LBL E ENTER STO 5 2 x pi x Sqr RCL 5 RCL 5 2 / Y^x STO 6 x RCL 5 e^x 1/x x STO x6 RCL 5 1/x ENTER ENTER ENTER RCL 1 x RCL 2 + x RCL 3 + x RCL 4 + x 1 + RCL 6 x RTN

Instruction:
1. Press [A] Initialize
2. Press [E] for x!

Example: [A] Initialize then 4.25 [B]
result approximation 35.21
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 Messages In This Thread (HP65) Factorial and Gamma Function - Gamo - 10-21-2017 08:32 AM RE: (HP65) Factorial and Gamma Function - Dieter - 10-21-2017, 01:21 PM RE: (HP65) Factorial and Gamma Function - Dieter - 10-21-2017, 08:01 PM RE: (HP65) Factorial and Gamma Function - Gamo - 10-22-2017, 02:40 AM RE: (HP65) Factorial and Gamma Function - Dieter - 10-22-2017, 05:28 PM RE: (HP65) Factorial and Gamma Function - peacecalc - 10-22-2017, 08:49 AM RE: (HP65) Factorial and Gamma Function - Dieter - 10-24-2017, 06:34 PM RE: (HP65) Factorial and Gamma Function - Gamo - 10-25-2017, 12:26 AM RE: (HP65) Factorial and Gamma Function - peacecalc - 10-25-2017, 04:06 PM RE: (HP65) Factorial and Gamma Function - Dieter - 10-26-2017, 06:59 AM RE: (HP65) Factorial and Gamma Function - Massimo Gnerucci - 10-26-2017, 07:11 AM RE: (HP65) Factorial and Gamma Function - Dieter - 10-26-2017, 05:34 PM RE: (HP65) Factorial and Gamma Function - Massimo Gnerucci - 10-26-2017, 08:11 PM RE: (HP65) Factorial and Gamma Function - peacecalc - 10-26-2017, 03:41 PM RE: (HP65) Factorial and Gamma Function - pier4r - 10-27-2017, 08:06 AM RE: (HP65) Factorial and Gamma Function - toml_12953 - 10-27-2017, 02:26 PM RE: (HP65) Factorial and Gamma Function - Gamo - 10-27-2017, 01:57 PM

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