Trig algorithms on HP RPN?

[Idnarn]

(Yesterday 01:39 PM)MinkLib Wrote:  Can someone tell me if the trig algorithms for HP (and other RPN calculators) are all done in radians (behind the scenes).

While the answer cannot be generalized as it may depend on the particular calculator, if you want an example, see the paper "Algorithms and Accuracy in the HP-35" by David S. Cochran (example, here: https://www.keesvandersanden.nl/calculat..._HP-35.pdf) which describes trigonometry function calculation on the HP-35. I read somewhere (was it an interview with William Kahan?) that the HP 15C code derived from it.

You can also browse Jacques Laporte's excellent reverse engineering of the HP-35 here: https://archived.hpcalc.org/laporte/index.html

https://archived.hpcalc.org/laporte/Trigonometry.htm