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Reference for Processing version 1.0+. If you have a previous version, use the reference included with your software. If you see any errors or have any comments, let us know.

Name

### atan2()

Examples

    void draw() {
      background(204);
      translate(width/2, height/2);
      float a = atan2(mouseY-height/2, mouseX-width/2);
      rotate(a);
      rect(-12, -5, 24, 10);
    }

Description

Calculates the angle (in radians) from a specified point to the coordinate origin as measured from the positive x-axis. Values are returned as a float in the range from PI to -PI. The atan2() function is most often used for orienting geometry to the position of the cursor. Note: The y-coordinate of the point is the first parameter and the x-coordinate is the second due the the structure of calculating the tangent.

Syntax

    atan2(y, x);

Parameters

y | int or float: y-coordinate of the point
x | int or float: x-coordinate of the point

Returns | float
Usage | Web & Application
Related | tan()

Updated on November 22, 2008 08:39:25pm PST