Kelvin Functions for the HP-65

This program is Copyright © 1974 by Hewlett-Packard and is used here by permission. This program was originally published in the HP-65 Math Pac 2.

This program is supplied without representation or warranty of any kind. Hewlett-Packard Company and The Museum of HP Calculators therefore assume no responsibility and shall have no liability, consequential or otherwise, of any kind arising from the use of this program material or any part thereof.

Card Labels

Kelvin Functions
Label
Key	A	B	C	D	E

Overview

               (.25x2)2     (.25x2)4
ber(x) = 1 -  ---------- + --------- - . . .
                (2!)2        (4!)2

                  (.25x2)3     (.25x2)5
bei(x) = .25x2 - ---------- + ---------- - . . .
                   (3!)2        (5!)2

This program computes successive partial sums of the series. The program stops and displays the last partial sum as the answer, when two consecutive partial sums are equal or more than 50 terms have been added.

Notes:
1. When x is too large, computing a new term of the series might cause an overflow, in that case, display shows all 9's and the program stops.

2. ber (-x) = ber (x), bei (-x) = bei (x)

Instructions

Examples

1. ber (4.4) = -3.93
2. bei (0.6) = 0.09

The Program

 CODE  KEYS
   23  LBL
   11  A
   41  ENTER↑
   71  ×
   41  ENTER↑
   71  ×
33 03  STO 3
35 00  g LST x
   04  4
   81  ÷
35 08  g R↓
   44  CLX
33 02  STO 2
35 07  g x⇔y
33 01  STO 1
35 23  g x=y
   01  1
35 08  g R↓
35 09  g R↑
33 05  STO 5

   23  LBL
   01  1
   41  ENTER↑
33 04  STO 4
34 05  RCL 5
   61  +
35 23  g x=y
   24  RTN
   24  RTN
   43  EEX
   02  2
34 02  RCL 2
   02  2 
   61  +
33 02  STO 2
35 24  g x>y
34 04  RCL 4
   24  RTN
34 01  RCL 1
   61  + 
   41  ENTER↑
   71  ×
35 00  g LST x
   51  -
   41  ENTER↑
   71  ×
   08  8
   00  0
   71  ×
   05  5
   42  CHS
34 03  RCL 3
   71  ×
35 07  g x⇔y
   81  ÷
34 05  RCL 5
   71  ×
33 05  STO 5
34 04  RCL 4
   61  +
   22  GTO
   01  1
35 01  g NOP
35 01  g NOP 
35 01  g NOP 
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 01  g NOP
35 n1  g NOP

Register Use

R1  0 or 1
R2  used
R3  x4
R4  used
R5  used
R6
R7
R8
R9  used

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