cos(x) sin(x) tan(x) acos(x) asin(x) atan(x) atan2(y, x)
atan2(y,x)
returns the angle
between the x-axis and the vector from the origin to (x,y), i.e., for
positive arguments atan2(y,x) == atan(y/x)
.
Angles are in radians, not degrees (i.e. a right angle is &pi/2).
Log
, Math
.cos(0) == 1 sin(3*pi/2) == cos(pi) x <- rnorm(99) all( sin(-x) == - sin(x)) all( cos(-x) == cos(x)) x <- abs(x); y <- abs(rnorm(x)) all(abs(atan2(y, x) - atan(y/x)) <= .Machine$double.eps)# TRUE table(abs(atan2(y, x) - atan(y/x)) / .Machine$double.eps) # depends! x <- 1:99/100 all(Mod(1 - (cos(x) + 1i*sin(x)) / exp(1i*x)) < 1.1 * .Machine$double.eps) 2* abs(1 - x / acos(cos(x))) / .Machine$double.eps #-- depends ? all(abs(1 - x / asin(sin(x))) <= .Machine$double.eps) # TRUE all(abs(1 - x / atan(tan(x))) <= .Machine$double.eps) # TRUE