# Lituus

From JSXGraph Wiki

A **lituus** is a spiral in which the angle is inversely proportional to the square of the radius (as expressed in polar coordinates).

- [math]\displaystyle{ r^2\theta = k \, }[/math]

### The JavaScript code to produce this picture

```
<jsxgraph width="500" height="500" box="box1">
var b1 = JXG.JSXGraph.initBoard('box1', {axis:true,originX: 250, originY: 250, unitX: 25, unitY: 25});
var k = b1.create('slider', [[1,8],[5,8],[0,1,4]]);
var c = b1.create('curve', [function(phi){return Math.sqrt(k.Value()/phi); }, [0, 0],0, 8*Math.PI],
{curveType:'polar', strokewidth:1});
</jsxgraph>
```