add polar_coordinate

README.md

@@ -144,7 +144,7 @@ These examples incubate dotSCAD and dotSCAD refactors these examples. See [examp
 - [util/has](https://openhome.cc/eGossip/OpenSCAD/lib3x-has.html)
 - [util/lerp](https://openhome.cc/eGossip/OpenSCAD/lib3x-lerp.html)
 - [util/parse_number](https://openhome.cc/eGossip/OpenSCAD/lib3x-parse_number.html)
-- util/polar_coordinate
+- [util/polar_coordinate](https://openhome.cc/eGossip/OpenSCAD/lib3x-polar_coordinate.html)
 - [util/radians](https://openhome.cc/eGossip/OpenSCAD/lib3x-radians.html)
 - [util/rand](https://openhome.cc/eGossip/OpenSCAD/lib3x-rand.html)
 - [util/reverse](https://openhome.cc/eGossip/OpenSCAD/lib3x-reverse.html)

docs/lib3x-polar_coordinate.md

@@ -0,0 +1,18 @@
+# polar_coordinate
+
+Converts from Cartesian to Polar coordinates.
+
+**Since:** 3.0
+
+## Parameters
+
+- `point` : The Cartesian coordinates (also called rectangular coordinates) of a point.
+
+## Examples
+
+    use <util/polar_coordinate.scad>;
+    
+	coord = polar_coordinate([100, 100]);
+	r = round(coord[0]);
+	theta = round(coord[1]);
+    assert([r, theta] == [141, 45]);  

src/util/polar_coordinate.scad

@@ -1,3 +1,13 @@
+/**
+* polar_coordinate.scad
+*
+* @copyright Justin Lin, 2020
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib3x-polar_coordinate.html
+*
+**/ 
+
 use <../__comm__/__angy_angz.scad>;
 
 function polar_coordinate(point) = [norm(point), atan2(point[1], point[0])]; // r, theta