complex exponents for e

[Ed Look]

Neither the 50g nor 49g+ seem to be able to give me EXP(ix). I get some error message that I can't do this in EQW mode.

Is this a bug? (Or is it me??)

[Luiz C. Vieira (Brazil)]

Hi, Ed;

have you checked the syntax OR mode/FLAG set? I am not with an HP49G in hands right now, but it crossed my mind...

Success!

Luiz (Brazil)

[Ed Look]

Luiz, thanks for the ideas!

I will look again at my syntax; I know I'm no expert at the equation writer or CAS in the 50g/49g+. To confess, I've really only just started (less than a week ago! And I've been using and programming these calculators for a while now! I've never until now felt the desire to plot anything on them.)

Also, I will explore the flags. It is very possible something isn't set the way I want it to be.

Edited: 15 Nov 2012, 12:27 a.m.

[Luiz C. Vieira (Brazil)]

Hi, Ed.

I tried the keyboard [e^x] and it worked fine with a complex argument (0,5). My HP50G still has the default settings, IIRC. The 4MByte big, 639-page long HP50G AURM has a brief description at page #198 (3-78).

Cheers.

Luiz (Brazil)

[Ed Look]

Yeah, it should work fine in normal calculations.

However, the Equation Writer in the 50g/49g+ does not seem to allow the inclusion of an imaginary exponent when e is the base.

I mean, if you type it from the keyboard and then run a calculation it does work. But say, if I want to plot it on graph on the calculator, then I cannot even get past trying to write the expression, as I get an error message saying I can't do that. But the next second, everything looks fine, I finish writing the equation with my complex exponent with the base e...

... and it won't plot.

[George Litauszky]

You can plot complex expressions with the Gridmap mode,with Parametric plot, or in Fast3D with ABS(Compl.Expression) format. See this posts.

Post 1

Post2

[Ed Look]

George, thanks.

First chance I get I'll read them.

[Paul Dale]

Just get a 34S and enjoy effortless complex exponentials.....

- Pauli

[Ángel Martin]

... or the 41Z module for VINTAGE effortless complex exponentials :-)

just kidding of course but I couldn't resist.

Although on the CL it has a complete new twist, you must see those complex functions returning instantaneous results - definitely the way the 41 was meant to be.

[Ed Look]

Heh heh...
... I have a dead one on my desk right now, and haven't the time yet to muck with it to try to make it work. But even then, it doesn't graph, which is what I'm trying to do currently.

[Paul Dale]

With the IR diode addition, it can graph to a printer :-) It can graph to the unequaled dot matrix portion of its display as well...

Porting HP's graphing and plotting code from one of the 41c modules should be straightforward enough. I started but got sidetracked.

- Pauli

[Bart (UK)]

Hi Ed,

Are you remembering to use the multiply key? "ix" is a symbol (i.e. variable with the name ix that you haven't defined), "i.x" is imaginary x. Even with numbers "i5" is a symbol and "i.5" => "0+5i".

Edited: 16 Nov 2012, 5:24 a.m.

[Ed Look]

Bart, I tried it both ways.

But the error message came up before this step! When I try first to access the CMPLX menu in Equation Writer, the error message pops up.

[Bart (UK)]

OK, that's wierd. I can use the CMPLX menu in the equation writer and enter e^i.X without any problem, even in real mode (flag -103 clear & -128 set, actually mine works with any combination of these 2 flags). Sounds like your calculator has it's nickers in a twist. Have you tried resetting the calculator? (with ON-F1-F6 !!backup data first!!)

[Ed Look]

Yipes. I hope it doesn't come to that. Backing up a calculator, even one with a USB connection to a PC, is a pain in the neck. I *think* I have my programs backed up on my PC, and hopefully, some SD card somewhere in a drawer.

But, I'll keep at this... and probably continue to bug all of you.

[Bart (UK)]

You can try a warm reset with ON-F3 which should keep memory intact. However, a full reset is a more reliable way to recover a buggy calculator.


Edit
On re-reading your original post, you mention having the problem on both the 50g & 49g+. It is unlikely that two calculators have the same problem at the same time.
Can you:

• Give the S/W version of each calculator? (type VERSION enter)
• Give the flags of each (type RCLF and report it as e.g. { # 1A0010204190FF0h # 0h # 805000002A000016h # 0h })
• the exact steps (keypresses) you are taking

I will try to duplicate the problem.

Edited: 19 Nov 2012, 5:07 a.m.

[Ed Look]

I will do that as soon as I can, and thanks!

However, last night, on a whim, I tried exactly what I did last time, although, I bore your advice to use the multiplication operator instead of just typing "iX", in mind.

I GOT NO ERROR MESSAGE!

And it plotted... not the way I expected, but it did plot. I suppose, that is progress of sorts.

Now allow me to confess- I was trying to plot Y(X)=[(e^iX)-(e^-iX)]/2i, (i.e., sin(X), if memory serves, though my memory isn't what it was) just to see what would happen. (I just didn't expect error messages to have cropped up.) Perhaps if there was a way to define or declare a complex mode for the axes or space in the plot itself... I am not as versed in the 50g/49g+ environment as I should be.