Mellin
March 11, 2017, 8:21pm
1
Inverse trigonometric functions, or cyclometric functions:

arcus sinus - arcsin(x)
arcus cosinus - arccos(x)
acrus tangent - arctan(x)
arcus tangent 2 - arctan2(x,y)

They would be really helpful, when going from the cartesian coordinate system into a polar coordinate system.

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Looking at what is need to provide ‘Islamic Calendar’ … which is based on declination of Sun.

This will need: `asin(x)`

, `acos(x)`

, and `atan2(x, y)`

Discussed here:

Facer has an atan function that works in the designer, however it does not work on the actual watch (neither do asin or acos). Unfortunately, Facer refuses to even acknowledge* the problem, much less solve it. You can however, approximate atan, with some error. Obviously, this is not ideal, but then the whole situation isn't ideal, so here you go:
atan(x) ≈ (((pi*x*(0.596227+x))/(2*x*(1.192454+x)+2)-(pi*(0.596227-x)*x)/(2*(x-1.192454)*x+2))*(1+abs(x)/x))/2+(pi*(0.596227-x)*x)/(2*(x-1.192454)*x…
“Facer has an atan function that works in the designer, however it does not work on the actual watch (neither do asin or acos ). … You can however, approximate atan , with some error … ”

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