November 2001
Intermediate to advanced
936 pages
68h 43m
English
Math.atan2( ) — compute the angle from the X-axis to a point
JavaScript 1.0; JScript 1.0; ECMAScript v1
Math.atan2(y,x)
y
The Y-coordinate of the point.
x
The X-coordinate of the point.
A value between -π and π radians that specifies the
counterclockwise angle between the positive X-axis and the point
(x, y).
The Math.atan2( ) function computes the arc
tangent of the ratio
y/x. The
y argument can be considered the
Y-coordinate (or “rise”) of a point, and the
x argument can be considered the
X-coordinate (or “run”) of the point. Note the unusual
order of the arguments to this function: the Y-coordinate is passed
before the X-coordinate.