Imaginary numbers in 33S equation mode « Next Oldest | Next Newest »

 ▼ RB Junior Member Posts: 4 Threads: 1 Joined: Jan 1970 11-11-2004, 03:18 AM Hi. I'm trying to put an equation in my 33S involving complex numbers, but there's no apparent way to enter i. For example, how would I enter the equation y=x+i in my 33S (i being the unit imaginary)? Thanks ▼ Mike H Member Posts: 74 Threads: 14 Joined: Jul 2007 11-11-2004, 10:40 AM The 33 uses the expression Z=X+Yi for complex numbers. Like you I could not use the CMPX function in an equation. It did work when I wrote a program however. From the learning module on Complex numbers the following example is given: (3+2i)/(4-4i) The answer is 0.125 + 0.625i. Programming the 33S as follows C001 LBL C C002 RCL A C003 Enter C004 RCL B C005 Enter C006 RCL C C007 Enter C008 RCL D C009 CMPLX/ Store 3 in A Store 2 in B Store -4 in C Store 4 in D R/S results 0.6250 0.1250 I am no programmer, so I am sure there are better ways to express the program, but at least will allow you to enter imaginary parts into an equation. Mike Edited: 11 Nov 2004, 10:42 a.m. ▼ John Senior Member Posts: 348 Threads: 74 Joined: Jun 2013 11-11-2004, 10:43 AM I thought that RCL A RCL B RCL C RCL D would fill the stack with 4 numbers. Does the 33S require ENTER between those in a program? ▼ Mike H Member Posts: 74 Threads: 14 Joined: Jul 2007 11-11-2004, 10:53 AM - RB Junior Member Posts: 4 Threads: 1 Joined: Jan 1970 11-12-2004, 02:57 PM Thanks for the reply. I was actually trying to use complex numbers in the equation mode (where you input an equation and it solves for a variable), but I'm glad I can at least write programs with complex support. Thanks. Eddie Shore Senior Member Posts: 260 Threads: 40 Joined: Jan 1970 11-11-2004, 10:42 AM Unfortunately, equations on the HP33s does not support complex numbers. The i is used as an indirection variable rather than SQRT(-1). ▼ RB Junior Member Posts: 4 Threads: 1 Joined: Jan 1970 11-12-2004, 02:56 PM Thats terrible! I finally find a good use for equation mode, and it can't do what I want! Complex support really seem to be lacking on the 33S, I'm actually regretting buying it now. Thanks. ▼ Tony Aponick Junior Member Posts: 1 Threads: 0 Joined: Jan 1970 11-16-2004, 05:06 AM Just out of curiosity, what is the equation you want to solve with complex numbers?? Often if you just plug in (a + ib) into the equation, you can solve the real and imaginary parts separately. These separated equations *can* be solved numerically on the calculator ▼ RB Junior Member Posts: 4 Threads: 1 Joined: Jan 1970 11-16-2004, 10:59 PM The equation was sqrt[(R + jwL)/(G + jwc)]. It was tedious to retype this equations for various values. I know it would be simple to seperate it into real and imaginary parts, but I figured the equation mode could handle it. ▼ Karl Schneider Posting Freak Posts: 1,792 Threads: 62 Joined: Jan 2005 11-17-2004, 03:45 AM Quote: The equation [to be used in an equation for solving] was "sqrt[(R + jwL)/(G + jwc)]." This expression can be used within a program fed to the SOLVE function, which will solve for only one real-valued variable at a time: ``` x y z t RCL L RCL W * RCL R RCL C RCL W * RCL G G wC R wL CMPLX/ 0 ENTER 0.5 CMPLXyx ``` This will place Re {sqrt[(R + jwL)/(G + jwc)]} in the x-register and Im {sqrt[(R + jwL)/(G + jwc)]} in the y-register. Taking to the 0.5 power is the only workaround for finding square roots of complex-valued arguments. -- KS Edited: 17 Nov 2004, 3:46 a.m.

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