[Python-ideas] Trigonometry in degrees

Steven D'Aprano steve at pearwood.info
Fri Jun 8 08:25:13 EDT 2018


On Fri, Jun 08, 2018 at 06:34:25PM +1200, Greg Ewing wrote:

> I'm not sure what all the fuss is about:
> 
> >>> from math import pi, sin
> >>> sin(pi/2)
> 1.0

Try cos(pi/2) or sin(pi/6).

Or try:

sin(pi/4) == sqrt(2)/2
tan(pi/4) == 1
tan(pi/3) == sqrt(3)

And even tan(pi/2), which ought to be an error, but isn't.

These are, of course, limitations due to the finite precision of floats.

But Julia gets the equivalent degree-based calculations all correct, 
except for tan(90) where it returns Inf (NAN would be better, as the 
limit from below and the limit from above are different).


-- 
Steve


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