The
ATAN function returns the
angle, expressed in radians, whose tangent is *
X*
(i.e., the
arc-tangent). If two parameters are supplied, the angle whose tangent is equal to *
Y/X*
is returned. The range of ATAN is between -*
p*
/2 and *
p*
/2 for the single argument case, and between -*
p*
and *
p*
if two arguments are given.

To find the arc-tangent of 0.707 and store the result in the variable B, enter:

The following code defines a function that converts Cartesian coordinates to polar coordinates. It returns "r" and "theta" given an "x" and "y" position:

FUNCTION TO_POLAR, X, Y *;
Define function TO_POLAR that accepts X and Y as arguments.*

RETURN, [SQRT(X^2 + Y^2), ATAN(Y, X)]

*;
Return the distance and angle as a two-element array.*