Hi, does anyone know if there is an object to calculate the inverse of cos?
i mean arccos of course, there is a way to evaluate it but is a bit expensive for the cpu:

sin(t)^2 + cos(t)^2 = 1
so
sin(arccos(x)) = sqrt(1-x^2)
so
tan(arccos(x)) = sin(arccos(x))/cos(arccos(x)) = sqrt(1-x^2)/x
so
arccos(x) = arctan(tan(arccos(x))) = arctan(sqrt(1-x^2)/x)

try [expr acos(value)]