The Museum of HP Calculators

HP Forum Archive 17

 (deleted post)Message #1 Posted by deleted on 10 Oct 2007, 9:52 a.m. This Message was deleted. This empty message preserves the threading when a post with followup(s) is deleted. If all followups have been removed, the original poster may delete this post again to make this placeholder disappear.

 Re: HP 35s problem with complex numbers.Message #2 Posted by Gene Wright on 10 Oct 2007, 2:42 p.m.,in response to message #1 by deleted How are you trying to enter such a complex number? I know you can press 3 i 4 and get that complex number on the stack, but what are you pressing to create a complex number using a variable or a constant? Give us a specific example of what keys you're pressing (or what equation you're trying) and that will help.

 Re: HP 35s problem with complex numbers.Message #3 Posted by Ike on 10 Oct 2007, 3:05 p.m.,in response to message #2 by Gene Wright I wanted to try Euler's equation: e^(i(pi)) + 1 = 0 For the exponent if I enter "0 i 3.14" where I manually enter an estimate of pi, I'm OK If I enter "0 i shift pi" I am left with pi in the real portion of the number with no imaginary component and who know what in rectangular form in the Y register above it. This is very perplexing. So I tried storing pi in the "a" register and tried: "0 i RCL a" and I get the same kind of nonsensical result. It sure is frustrating. Edited: 10 Oct 2007, 3:07 p.m.

 Re: HP 35s problem with complex numbers.Message #4 Posted by Gene Wright on 10 Oct 2007, 3:48 p.m.,in response to message #3 by Ike The reason is because you cannot build complex numbers from values in registers or constants in the manner you are trying. You can see this in a program. In program mode, press EQN to turn on equation mode and type: RCL B then i then 2 Now leave program mode and single-step that program line. You get a syntax error. Try the approach shown in the next posting. Edited: 10 Oct 2007, 4:07 p.m. after one or more responses were posted

 Re: HP 35s problem with complex numbers.Message #5 Posted by Ike on 10 Oct 2007, 4:06 p.m.,in response to message #4 by Gene Wright Gene, Thanks for your thoughtful response even though it isn't what I wanted to hear! It's too bad a complex variable cannot be constructed from constants or a register - why should the calculator care where the number comes from? Oh well, on to the next problem like world peace or some such thing. Cheers, Ike

 Re: HP 35s problem with complex numbers.Message #6 Posted by Egan Ford on 10 Oct 2007, 3:58 p.m.,in response to message #3 by Ike Try: PI i * e^x 1 + With a reg: i RCL* P e^x 1 +

 Re: HP 35s problem with complex numbers.Message #7 Posted by Ike on 10 Oct 2007, 4:10 p.m.,in response to message #6 by Egan Ford Egan, I will try your steps when I get home for there is where I left my HP35s. I will certainly let you know the outcome unless someone has a 35s with them now and can try your procedure. Thanks, Ike

 Re: HP 35s problem with complex numbers.Message #8 Posted by Karl Schneider on 10 Oct 2007, 10:31 p.m.,in response to message #3 by Ike Ike -- Egan Ford's previous response is correct. The reason for the seemingly-inconsistent behavior is that hitting the pi key terminates data entry and pushes pi onto the stack. A previously-entered "i" then becomes a complete number, represented as "0i1" (0 + i1). Multiplying pi by "i" in either order produces the value you wanted. I have made detailed suggestions to HP's calculator team for improving the complex-number functionality, and will continue to follow up on them. Help may be on the way, if you're willing to wait a number of months. -- KS

 Re: HP 35s problem with complex numbers.Message #9 Posted by Ike on 10 Oct 2007, 11:28 p.m.,in response to message #8 by Karl Schneider Karl, Yes, Eagan is correct especially in the first solution. I had a bit more problem with the second but I'm not going to worry about it anymore. The bottom line is that now with the help from you folks I have something I can live with - thanks! Now get those HP folks in line! Cheers! Ike

 Re: HP 35s problem with complex numbers.Message #10 Posted by Egan Ford on 10 Oct 2007, 11:38 p.m.,in response to message #9 by Ike For the 2nd: 1. Put a value in a register, e.g. A 2. Then type: i RCL* A i.e. RCL, then x (times), then A, aka recall arithmetic. Or to make it easy: i RCL A * Both will build you a complex number from registers. For A+iB: number STO A number STO B i RCL* B RCL+ A OR i RCL B * RCL A +

 Re: HP 35s problem with complex numbers.Message #11 Posted by Trent Moseley on 11 Oct 2007, 10:06 p.m.,in response to message #8 by Karl Schneider Karl - I'm numb with this stuff. Having solved all complex problems with the 42s why did HP need to reinvent the wheel? tm

 Re: HP 35s problem with complex numbers.Message #12 Posted by DaveJ on 11 Oct 2007, 10:54 p.m.,in response to message #11 by Trent Moseley Quote: Karl - I'm numb with this stuff. Having solved all complex problems with the 42s why did HP need to reinvent the wheel? Two reasons: 1) Companies are ruled by marketing. 2) There is no such thing as one tool for every job. Dave.

 Re: HP 35s problem with complex numbers.Message #13 Posted by Trent Moseley on 11 Oct 2007, 11:24 p.m.,in response to message #12 by DaveJ Dave- You missed my point. tm

 Re: HP 35s problem with complex numbers.Message #14 Posted by DaveJ on 11 Oct 2007, 11:59 p.m.,in response to message #13 by Trent Moseley Quote: You missed my point. Ok, sorry, what was your point? Dave.

 Re: HP 35s problem with complex numbers.Message #15 Posted by Karl Schneider on 12 Oct 2007, 1:04 a.m.,in response to message #11 by Trent Moseley Hi, Trent -- Quote: Having solved all complex problems with the 42s why did HP need to reinvent the wheel? Well, I can't fully concur on that point. I have yet to see a calculator from any manufacturer having ideal complex-number functionality, but certainly the HP-42S is among the best. Its display of complex numbers is perfect, but the HP-42S lacks the following: Direct, one-step entry of complex numbers in rectangular or polar form in either "mode" (as the HP-35s has) A menu of complex-number functions (as the HP-28C/S has) Mixed-mode display of complex numbers with most-reasonable result format (Simple and straightforward, but I've never seen it done -- by HP or by TI or Casio in the models I've examined) Details will follow, hopefully within a week. Here's a sample: -- KS

 i^2 = invalid data in one caseMessage #16 Posted by DavidB on 11 Oct 2007, 1:10 a.m.,in response to message #1 by deleted In mathematics, the square of imaginary unit i is -1. If I enter the imaginary number 0i1 and then take the square of it (x^2), the HP 35s displays "INVALID DATA." The same happens when I enter any complex number and take the square of it using the x^2 key on the calculator. If I enter the following, as shown in manual, p. 9-5: 1i1 ENTER 2 (positive 2 here) y^x The result is 0i2, since (1 + i)^2 = 1^2 + i + i + i^2 = 1 + 2i -1 = 0 + 2i So, in one way, the 35s does compute i^2. But just using x^2 will not work. If I enter: i 1 ENTER 2 y^x I get the result as -1i0 (or -1 + 0i). I originally thought the 35s did not compute i^2 at all, but it does. As noted in the manual, you can y^x to compute powers of a complex number. Cheers! David Bailey Edited: 11 Oct 2007, 1:51 a.m.

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