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| The Processing 1.0 _ALPHA_ Reference is a work in progress. If you see any errors or have any comments, please write to: reas at groupc.net

Name |  | ### atan2()
Examples |  |
    void loop() {
      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()

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| Processing is an open project initiated by Ben Fry and Casey Reas |