Difference between revisions of "LlAtan2"

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m (Mathematically speaking I don't think there was anything wrong with the previous version (i think they are equivalent) regardless, spaces are needed, it's an example after all!)
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|return_type=float
 
|return_type=float
 
|return_text=that is the {{wikipedia|Atan2|arctangent2}} of '''y''', '''x'''.
 
|return_text=that is the {{wikipedia|Atan2|arctangent2}} of '''y''', '''x'''.
|func_footnote=Similar to the <span class="plainlinks">{{wikipedia|Inverse_trigonometric_functions|arctangent}}</span>('''y'''/'''x''') except it utilizes the signs of '''x''' & '''y''' to determine the quadrant. Returns zero if '''x''' and '''y''' are zero.<br />
+
|func_footnote=Similar to the <span class="plainlinks">{{wikipedia|Inverse_trigonometric_functions|arctangent}}</span>('''y'''/'''x''') except it utilizes the signs of '''x''' & '''y''' to determine the quadrant and avoids  division by zero. Returns zero if '''x''' and '''y''' are zero, returns '''PI/2''' if '''x''' is zero and '''y'''  is positive, returns '''-PI/2''' if '''x''' is zero and '''y''' is negative.<br />
 
The returned value is in the range {{Interval|gte=-[[PI]]|gteh=-PI|lte=PI|center=return}}{{Interval/Footnote}}.
 
The returned value is in the range {{Interval|gte=-[[PI]]|gteh=-PI|lte=PI|center=return}}{{Interval/Footnote}}.
 
|spec
 
|spec

Revision as of 10:14, 3 May 2011

Summary

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 and avoids division by zero. Returns zero if x and y are zero, returns PI/2 if x is zero and y is positive, returns -PI/2 if x is zero and y is negative.
The returned value is in the range [-PI, PI][1].

Examples

<lsl>default {

 state_entry()
 {
   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 :-) //corrected by Patrick Muggins

string compass (vector target) {

   vector source = llGetPos();
   list DIRS =["W","NW","N","NE","E","SE","S","SW","W"];
   integer index = llCeil(3.5 - (4 * llAtan2(target.y - source.y, target.x - source.x) / PI));
   return llList2String(DIRS, index);

}</lsl>

/Compass QA

See Also

Functions

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

Articles

•  Wikipedia:Atan2
•  Wikipedia:Inverse_trigonometric_function

Deep Notes

Search JIRA for related Issues

Footnotes

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

Signature

function float llAtan2( float y, float x );