The Museum of HP Calculators

HP Forum Archive 17

 ATAN2 on 35SMessage #1 Posted by Vincze on 14 Aug 2007, 4:07 p.m. Can the 35s perform the ATAN2 function as a built in function? I have not found it and I am in need of it.

 Re: ATAN2 on 35SMessage #2 Posted by Gene Wright on 14 Aug 2007, 4:09 p.m.,in response to message #1 by Vincze Not as a built-in function. You'll have to use several lines of code. Edited: 14 Aug 2007, 4:35 p.m.

 Re: ATAN2 on 35SMessage #3 Posted by Thomas Radtke on 14 Aug 2007, 4:12 p.m.,in response to message #1 by Vincze You could construct a komplex number x+iy and apply ARG. This is what I do in my R > P implementation.

 Re: ATAN2 on 35SMessage #4 Posted by Vincze on 14 Aug 2007, 4:22 p.m.,in response to message #3 by Thomas Radtke I don't think I follow you. For example, if X = 10 and Y = 15, ATAN2 of those should be 0.982794. So you say to do following in RPN: ```i15 - ENTER - 10 ARG ``` When I do that, it yield 56.309932. Am I not understanding something?

 Re: ATAN2 on 35SMessage #5 Posted by Thomas Radtke on 14 Aug 2007, 4:28 p.m.,in response to message #4 by Vincze Your calc is in DEG mode while you brain works in RAD ;-). Just do a ->RAD conversion.

 Re: ATAN2 on 35SMessage #6 Posted by Vincze on 14 Aug 2007, 4:33 p.m.,in response to message #5 by Thomas Radtke okay... that make sense.

 MOD on 35SMessage #7 Posted by Vincze on 14 Aug 2007, 4:47 p.m.,in response to message #6 by Vincze Sorry, but I have one more question. Can 35s do MOD (Modular arithmetic)? Such as a float be x and I solve for MOD(x,2*PI).

 Re: MOD on 35SMessage #8 Posted by Thomas Radtke on 14 Aug 2007, 5:27 p.m.,in response to message #7 by Vincze I suppose you have the remainder in mind. Have a look at Chapter 4-2. (INT menu, 3Rmdr)

 Re: MOD on 35SMessage #9 Posted by Vincze on 14 Aug 2007, 5:33 p.m.,in response to message #8 by Thomas Radtke No, more like lets use simple clock example. Let say start time is 20:00 on 24 hour clock, and you need to add 5 hours to that, but you wish to have wrap around math, so with normal math you state 20:00 + 5:00 = 25:00, but that does not make sense on clock. With modular math, you would say 20:00 + 5:00 mod 24 = 1:00, meaning if you start at 8pm, and you need to add 5 hours to it, you would finish at 1am. In Excel the formula would be =mod(Start + End, 24). This used in aviation to work out degrees and the like. I will look at chapter you state and see if that give me a clue Edited: 14 Aug 2007, 5:35 p.m.

 Re: MOD on 35SMessage #10 Posted by Thomas Radtke on 14 Aug 2007, 5:43 p.m.,in response to message #9 by Vincze That's just the usual modulo, same menu, 2INT/

 Re: MOD on 35SMessage #11 Posted by Vincze on 14 Aug 2007, 7:21 p.m.,in response to message #10 by Thomas Radtke That does not work. See for example. 20:00 + 12:00 mod 24 = 08:00 If I enter the following on calculator: ```20 ENTER 12 + 24 INTG 2 ``` answer is 1 which is not correct. Time is easy to deal with, but when you dealing numbers that wrap around when reaching the modulus of 2 * PI, it a little harder to deal with. For calculation that I am doing, I need to simulate the Mod(x,y) function. Edited: 14 Aug 2007, 7:48 p.m.

 Re: MOD on 35SMessage #12 Posted by Don Shepherd on 14 Aug 2007, 8:11 p.m.,in response to message #11 by Vincze It's INTG 3 (remainder)

 Re: MOD on 35SMessage #13 Posted by Vincze on 14 Aug 2007, 8:13 p.m.,in response to message #11 by Vincze I think I figure out, at least with clock. Here is what I do. Let say we have 21:00 + 10:00 mod 24 = 07:00 35S work this way...``` 21 ENTER 10 + 24 / INTG 5 24 * ``` which yield 7. I have to now try this on other calculation that use strange mod and see if this will be correct. I guess I could make short program that could do this. Edited: 14 Aug 2007, 8:17 p.m.

 Re: MOD on 35SMessage #14 Posted by Karl Schneider on 15 Aug 2007, 2:31 a.m.,in response to message #13 by Vincze Quote: Let say we have 21:00 + 10:00 mod 24 = 07:00 The 35S works this way... ```21 ENTER 10 + 24 INTG 3 (Rmdr) ``` which yields 7. -- KS

 Re: MOD on 35SMessage #15 Posted by Vincze on 15 Aug 2007, 9:16 a.m.,in response to message #14 by Karl Schneider Yes, that a few steps shorter than mine.

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