Tangent and arctangent

tan x     tan[x]
atan x    atan[x]

Where x is a numeric, returns

tan

the tangent of x, taken to be in radians. Integer arguments are promoted to floating point. Null is returned if the argument is null or infinity.

The function is equivalent to {(sin x)%cos x}.

atan

the arctangent of x; that is, the value whose tangent is x.

The result is in radians and lies between \(-\frac{\pi}{2}\) and \(\frac{\pi}{2}\). The range is approximate due to rounding errors.

q)tan 0 0.5 1 1.5707963 2 0w                    / tangent
0 0.5463025 1.557408 3.732054e+07 -2.18504 0n

q)atan 0.5                                      / arctangent
0.4636476
q)atan 42
1.546991