[Python-ideas] Fwd: Trigonometry in degrees

Robert Kern robert.kern at gmail.com
Tue Jun 19 02:36:43 EDT 2018

On 6/18/18 19:23, Chris Barker via Python-ideas wrote:
> On Sat, Jun 16, 2018 at 10:57 PM, Tim Peters 
> <tim.peters at gmail.com 
> <mailto:tim.peters at gmail.com>> wrote:
>     Ya, decimal fp doesn't really solve anything except the shallow surprise
>     that decimal fractions generally aren't exactly representable as binary
>     fractions.  Which is worth a whole lot for casual users, but doesn't address
>     any of the deep problems (to the contrary, it makes those a bit worse).
> It's my suspicion that the story is the same with "degree-based" trig :-)
> Which is why, if you want "nice-looking" results, it seems one could simply 
> accept a decimal digit or so less precision, and use the "regular" FP trig 
> functions, rounding to 14 or so decimal digits.
> Though if someone really wants to implement trig in native degrees -- more power 
> to 'em.
> However -- if this is really such a good idea -- wouldn't someone have make a C 
> lib that does it? Or has someone? Anyone looked?

Certainly! scipy.special uses the functions implemented in the Cephes C library.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

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