# Python, NumPy, SymPy, mpmath, sage trigonometric functions
https://en.wikipedia.org/wiki/Trigonometric_functions
## Python math module
https://docs.python.org/3/library/math.html#trigonometricfunctions
 degrees(radians): Float degrees
 radians(degrees): Float degrees
## NumPy
https://docs.scipy.org/doc/numpy/reference/routines.math.html#trigonometric...
 degrees(radians) : List[float] degrees
 rad2deg(radians): List[float] degrees
 radians(degrees) : List[float] radians
 deg2rad(degrees): List[float] radians
https://docs.scipy.org/doc/numpy/reference/generated/numpy.sin.html
## SymPy
http://docs.sympy.org/latest/modules/functions/elementary.html#sympyfunctio...
http://docs.sympy.org/latest/modules/functions/elementary.html#trionometric...
 sympy.mpmath.degrees(radians): Float degrees
 sympy.mpmath.radians(degrees): Float radians
 https://stackoverflow.com/questions/31072815/cosdandsindwithsympy
 cosd, sind

https://stackoverflow.com/questions/31072815/cosdandsindwithsympy#commen...
> Let x, theta, phi, etc. be Symbols representing quantities in
radians. Keep a list of these symbols: angles = [x, theta, phi]. Then, at
the very end, use y.subs([(angle, angle*pi/180) for angle in angles]) to
change the meaning of the symbols to degrees"
## mpmath
http://mpmath.org/doc/current/functions/trigonometric.html
 sympy.mpmath.degrees(radians): Float degrees
 sympy.mpmath.radians(degrees): Float radians
## Sage
https://doc.sagemath.org/html/en/reference/functions/sage/functions/trig.htm...
On Friday, June 8, 2018, Robert Vanden Eynde
 Thanks for pointing out a language (Julia) that already had a name convention. Interestingly they don't have a atan2d function. Choosing the same convention as another language is a big plus.
 Adding trig function using floats between 0 and 1 is nice, currently one needs to do sin(tau * t) which is not so bad (from math import tau, tau sounds like turn).
 Julia has sinpi for sin(pi*x), one could have sintau(x) for sin(tau*x) or sinturn(x).
Grads are in the idea of turns but with more problems, as you guys said, grads are used by noone, but turns are more useful. sin(tau * t) For The Win.
 Even though people mentionned 1/6 not being exact, so that advantage over radians isn't that obvious ?
from math import sin, tau from fractions import Fraction sin(Fraction(1,6) * tau) sindeg(Fraction(1,6) * 360)
These already work today by the way.
 As you guys pointed out, using radians implies knowing a little bit about floating point arithmetic and its limitations. Integer are more simple and less error prone. Of course it's useful to know about floats but in many case it's not necessary to learn about it right away, young students just want their player in the game move in a straight line when angle = 90.
 sin(pi/2) == 1 but cos(pi/2) != 0 and sin(3*pi/2) != 1 so sin(pi/2) is kind of an exception.
Le ven. 8 juin 2018 à 09:11, Steven D'Aprano
a écrit : On Fri, Jun 08, 2018 at 03:55:34PM +1000, Chris Angelico wrote:
On Fri, Jun 8, 2018 at 3:45 PM, Steven D'Aprano
wrote: Although personally I prefer the look of d as a prefix:
dsin, dcos, dtan
That's more obviously pronounced "d(egrees) sin" etc rather than "sined" "tanned" etc.
Having it as a suffix does have one advantage. The math module would need a hyperbolic sine function which accepts an argument in; and then, like Charles Napier [1], Python would finally be able to say "I have sindh".
Ha ha, nice pun, but no, the hyperbolic trig functions never take arguments in degrees. Or radians for that matter. They are "hyperbolic angles", which some electrical engineering text books refer to as "hyperbolic radians", but all the maths text books I've seen don't call them anything other than a real number. (Or sometimes a complex number.)
But for what it's worth, there is a correspondence of a sort between the hyperbolic angle and circular angles. The circular angle going between 0 to 45° corresponds to the hyperbolic angle going from 0 to infinity.
https://en.wikipedia.org/wiki/Hyperbolic_angle
https://en.wikipedia.org/wiki/Hyperbolic_function
[1] Apocryphally, alas.
Don't ruin a good story with facts ;)
 Steve _______________________________________________ Pythonideas mailing list Pythonideas@python.org https://mail.python.org/mailman/listinfo/pythonideas Code of Conduct: http://python.org/psf/codeofconduct/