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JavaScript: The Definitive Guide, Fourth Edition
book

JavaScript: The Definitive Guide, Fourth Edition

by David Flanagan
November 2001
Intermediate to advanced content levelIntermediate to advanced
936 pages
68h 43m
English
O'Reilly Media, Inc.
Content preview from JavaScript: The Definitive Guide, Fourth Edition

Name

Math.atan2( ) — compute the angle from the X-axis to a point

Availability

JavaScript 1.0; JScript 1.0; ECMAScript v1

Synopsis

Math.atan2(y, x)

Arguments

y

The Y-coordinate of the point.

x

The X-coordinate of the point.

Returns

A value between -π and π radians that specifies the counterclockwise angle between the positive X-axis and the point (x, y).

Description

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.

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Publisher Resources

ISBN: 0596000480Supplemental ContentCatalog PageErrata