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HP Forum Archive 08

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Re: Polar to Rectangular etc. on the 48 Series
Message #1 Posted by Vieira, Luiz C. (Brazil) on 19 July 2002, 12:06 a.m.


just to add some info over Ron's answer.

It's stated in the 48's manual that it uses only rectangular-represented complex numbers as internal parameters; polar is a representation of those rectangular complex numbers.

If you use any HP calculator that does not work with complex numbers, then you use R->P and P->R with Y- and X-registers contents (HP11C, HP41, HP10C, HP25, among others). Both HP15C and HP42S maintain this feature, adding R->P and P->R to complex representations. While the HP15C will accept only rectangular complex numbers for calculus, the HP42S can work in any of both representations: Polar or Rectangular. That is, you can enter two polar-represented complex numbers and add them in the HP42S. You cannot do this in the HP15C, all you must do is enter each polar complex number, convert them to rectangular (each at a time), use them as you want and convert the result back to polar.

When I use complex numbers in the HP48, I only convert from Polar to Rectangular to show a particular result. I feel more comfortable knowing I do not need to worry about entering numbers in this or that mode (even 3D coordinates). If I need the elements of a particular representation, say, argument, absolute value, real or imaginary part, I use the functions to extract them from the defined mode and no longer will convert from one representation to another so I get those elements. Say, having ANY complex number in level 1, polar or rectangular mode, you can:

take its absolute value with ABS take its argument (angle) with ARG take its real part with RE take its imaginary part with IM

I must confess I miss these features in the earlier models. I admit that I got acquainted to them and I feel them somewhat closer to the actual meaning of the complex representations.

I hope this post gets useful for you.

Best regards.

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