These functions give the obvious trigonometric functions. They respectively compute the cosine, sine, tangent, arc-cosine, arc-sine, arc-tangent, and the two-argument arc-tangent.
cos(x) sin(x) tan(x) acos(x) asin(x) atan(x) atan2(y, x)
- x, y
- numeric or complex vectors.
Angles are in radians, not degrees (i.e., a right angle is π/2).
For the inverse trigonometric functions, branch cuts are defined as in Abramowitz and Stegun, figure 4.4, page 79.
atan there are two cuts, both along the pure imaginary axis: (-1i*Inf, -1i] and [1i, 1i*Inf).
The behaviour actually on the cuts follows the C99 standard which requires continuity coming round the endpoint in a counter-clockwise direction.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Abramowitz, M. and Stegun, I. A. (1972). Handbook of Mathematical Functions. New York: Dover.
Chapter 4. Elementary Transcendental Functions: Logarithmic, Exponential, Circular and Hyperbolic Functions
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