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(42S) Argument, Real Part, Imaginary Part, and Sign Function - Eddie W. Shore - 12-29-2018 05:25 AM
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).
Disclaimer: I don't own a DM42... yet.
HP 42S Program: ARG
Code:
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
Code:
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 ENDHP 42S Program: IMAG
Code:
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 ENDHP 42S Program: SIGN
Code:
00 { 15-Byte Prgm }
01▸LBL "SIGN"
02 X=0?
03 RTN
04 ENTER
05 ABS
06 X<>Y
07 ÷
08 RTN
09 ENDOriginal Blog Entry Link: https://edspi31415.blogspot.com/2018/12/hp-42sdm-42free42-argument-real-part.html
RE: (42S) Argument, Real Part, Imaginary Part, and Sign Function - Paul Dale - 12-29-2018 05:48 AM
What about:
Code:
LBL "SIGN"
x=0?
STO L
x=0?
RTN
ABS
x<> L
RCL/ L
RTNWhich (I think, I've no 42 to hand) sets LastX properly and doesn't impact the stack.
Pauli
RE: (42S) Argument, Real Part, Imaginary Part, and Sign Function - Thomas Klemm - 12-29-2018 06:35 AM
(12-29-2018 05:25 AM)Eddie W. Shore Wrote: The HP 42S* has only one extraction function for complex numbers: ABS (absolute value) by default.
(…)
Also included is the SIGN (signum) function.
What about using the built-in SIGN function?
RE: (42S) Argument, Real Part, Imaginary Part, and Sign Function - Dieter - 12-29-2018 08:50 AM
(12-29-2018 05:48 AM)Paul Dale Wrote: What about:
Code:
LBL "SIGN"
x=0?
STO L
x=0?
RTN
ABS
x<> L
RCL/ L
RTN
This would work if (!) the 42s allowed tests for complex numbers. ;-)
But it throws an "Invalid Type" error here.
(12-29-2018 06:35 AM)Thomas Klemm Wrote: What about using the built-in SIGN function?
Yes, a complex sign function is not required, the built-in function works nicely. For complex arguments it even returns 0 for 0+0i. For real arguments sign(0) is returned as 1. Maybe for compatibility with the HP-41 which does it the same way. Here SIGN returns 0 only for Alpha data (!).
Dieter
RE: (42S) Argument, Real Part, Imaginary Part, and Sign Function - Gerald H - 12-30-2018 07:12 PM
On my real HP 42S
SIGN
returns
0+0i
for input
0+0i
RE: (42S) Argument, Real Part, Imaginary Part, and Sign Function - Dieter - 12-30-2018 08:19 PM
(12-30-2018 07:12 PM)Gerald H Wrote: [ SIGN returns 0+0i for input 0+0i ]
Same for Free42. For complex arguments SIGN always returns a complex result.
Sorry, my description "...it even returns 0 for 0+0i" was inaccurate.
Dieter