Entering complex numbers in polar form??

[Michael Dickey]

Anyone know how to enter 2EXP(-j2pi/3) in its polar form, (2,/_ -2pi/3)
quickly without having to enter(2, /_ -2.094....)? I can't even figure
out how to enter the rectangular form, (-1, -SQRT(3)) without using:

(-1,0) ENTER (0,1) ENTER 3 SQRT NEG * +

This can be a real pain when you are using a lot of complex numbers...

I would appreciate any tips.

| Michael C. Dickey |
| LT, U.S. Coast Guard "Under Way is the ONLY way" |
| mdi...@coewl.cen.uiuc.edu |

[Goran Frehse]

About entering complex numbers:

1. (x,y)-format
In MATH/CMPL there is a command R->C that converts two reals into a
complex number.
Input: x [space] y R->C

To store this in the custom menu CST for easy access, you have to type
the command into a list:
{ R->C }
(the arrow is typed with alpha,right-shift,zero)
and type CST [STO]

2. (x,/_y)-format
Try the good old Euler in a function:
<< -> X << X i * EXP * >> >>

--

Goran Frehse, uj...@rzstud2.rz.uni-karlsruhe.de

[RHulbert]

The problem with the [R->C] and [C->R] commands is they always assume
rectangular format for input and output.

Try [MATH][VECTR][->V2]. If sysFlag -19 is set, this command results in
a complex number, if clear it assembles a vector from stack level 1 and 2.

The ->V2 command follows the setting of the polar/rectangle flag (-15).
If the polar mode is set it also follows the rad/deg mode.

Examples: {note: the <_ represents the angle sign (CHR 128)}

mode : DEG RECTANGULAR
2: 3
1: 4 ==> [->V2] ==> 1: (3, 4)

mode ==> DEG POLAR
2: 5
1: (5, <_ 53.13) ==> [V->] ==> 1: 53.13

mode : DEG POLAR
2: 5
1: 53.13 ==> [->V2] ==> 1: (5, <_ 53.13)

mode ==> RAD POLAR
2: 5
1: (5, <_ .93) ==> [V->] ==> 1: .93

mode : RAD POLAR
2: 5
1: .93 ==> [->V2] ==> 1: (5, <_ .93)

Rod

[jay...@kbbs.com]

Michael C. Dickey (mdi...@coewl.cen.uiuc.edu) writes:

> Anyone know how to enter 2EXP(-j2pi/3) in its polar form, (2,/_
> -2pi/3) quickly without having to enter(2, /_ -2.094....)? I can't
> even figure out how to enter the rectangular form, (-1, -SQRT(3))
> without using:
>
> (-1,0) ENTER (0,1) ENTER 3 SQRT NEG * +
>
> This can be a real pain when you are using a lot of complex
> numbers...
>
> I would appreciate any tips.

Set flag -19, then use the ->V2 function. (GX: MTH VECTR. SX: MTH
VECTR NXT). It's exactly what you're looking for. It takes two
numbers off the stack, and puts them directly into polar or
rectangular form, depending on whether you're in polar mode. With
flag -19 set, it'll be a complex number, which is what you want; with
flag -19 clear, it'll be a vector.

Pressing V-> splits a number in polar or rectangular form into its two
components; this too respects the current polar mode.

On the SX, you have a third very handy option: use the 2D key, which
does *both* ->V2 and V->, depending on the input. If you'd
like something similar on the GX, << IF DUP TYPE THEN V-> ELSE ->V2
END >> does the job.

-Joseph K. Horn- EQU jay...@kbbsnet.com
PS: Several folks have replied, "Use the R->C function". WRONG.
That function pays no attention to POLAR mode.

--
[*] Modem: (818) 886-0872 KBBS LOS ANGELES! ISDN:(818) 727-9218 [*]
[*] http://kbbs.kbbsnet.com Telnet: 204.96.25.7 Email: in...@kbbs.com [*]