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Function: float llAtan2( float y, float x );

Returns a float that is the arctangent2 of y, x.

• float y
• float x

Similar to the arctangent(y/x) except it utilizes the signs of x & y to determine the quadrant. Returns zero if x and y are zero.
The returned value is in the range [-PI, PI][1].


<lsl>default {

   float num1 = llFrand(100.0);
   float num2 = llFrand(100.0);
   llOwnerSay("y = " + (string)num1);
   llOwnerSay("x = " + (string)num2);
   llOwnerSay("The arctangent of y divided by x is " + (string)llAtan2(num1, num2));

}</lsl><lsl>//Function with input of a vector determining the position of a target and returning //a string with the literal compass-direction of that target towards your position //by Ramana Sweetwater 2009/01, any use allowed license :-)

string compass (vector target) {//-1.2732395447351 == -4/PI

   vector direction = target - llGetPos();
   list DIRS = [ "E", "SE", "S", "SW", "W", "NW", "N", "NE" ];
   integer index = llRound((llAtan2(direction.y, direction.x) * -1.2732395447351)) % 8;
   return llList2String(DIRS, index);


/Compass QA

See Also


• llSin llAsin sine & inverse Sine
• llCos llAcos cosine & inverse cosine
• llTan tangent


•  Wikipedia:Atan2
•  Wikipedia:Inverse_trigonometric_function

Deep Notes

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  1. ^ The ranges in this article are written in Interval Notation.


function float llAtan2( float y, float x );