Friday, December 28, 2018

HP 42S/DM 42/Free42: Argument, Real Part, Imaginary Part, and Sign Function

HP 42S/DM 42/Free42: Argument, Real Part, Imaginary Part, and Sign Function

Introduction

The HP 42S* has only one extraction function for complex numbers: ABS (absolute value) by default.  To complete the list, here are some programs for ARG (argument), REAL (real part), and IMAG (imaginary part).  The three functions take a complex number, in either rectangular or polar form. 

Using stack commands and flag checks, I am able to get obtain results without affecting the stack much (although the z and t stacks will have the same value).

Also included is the SIGN (signum) function.

* This applies to the Swiss Micros DM42 (it should work), Free42 from Thomas Oakken, and any other HP 42S emulator apps.  The print out is from Free42 (and I also have a physical HP 42S).

HP 42S Program: ARG

00 { 19-Byte Prgm }
01▸LBL "ARG"
02 COMPLEX
03 X<>Y
04 FC? 73
05 →POL
06 R↑
07 STO ST Y
08 R↓
09 R↓
10 RTN
11 .END.

HP 42S Program:  REAL

00 { 21-Byte Prgm }
01▸LBL "REAL"
02 COMPLEX
03 X<>Y
04 FS? 73
05 →REC
06 X<>Y
07 R↑
08 STO ST Y
09 R↓
10 R↓
11 RTN
12 END

HP 42S Program: IMAG

00 { 20-Byte Prgm }
01▸LBL "IMAG"
02 COMPLEX
03 X<>Y
04 FS? 73
05 →REC
06 R↑
07 STO ST Y
08 R↓
09 R↓
10 RTN
11 END

Example - Rectangular Mode:

7+8i   (7 [ENTER] 8 [ (shift) ] (COMPLEX) )
XEQ ARG:  48.8141 (Degrees)
XEQ REAL: 7.0000
XEQ IMAG: 8.0000

Example - Polar Mode: (Degrees):

4 ∡ 60  (4 [ENTER] 60 [ (shift) ] (COMPLEX) )
XEQ ARG:  60.0000
XEQ REAL:  2.0000
XEQ IMAG:  3.4641

HP 42S Program:  SIGN

00 { 15-Byte Prgm }
01▸LBL "SIGN"
02 X=0?
03 RTN
04 ENTER
05 ABS
06 X<>Y
07 ÷
08 RTN
09 END

Example:

-1.4641  XEQ SIGN returns -1
5.525 XEQ SIGN returns 1
0 XEQ SIGN returns 0

Eddie

All original content copyright, © 2011-2018.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.  Please contact the author if you have questions.

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