Difference between revisions of "Lituus"

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Line 24: Line 24:
 
  var b2 = JXG.JSXGraph.initBoard('box2', {axis:true,originX: 250, originY: 250, unitX: 25, unitY: 25});
 
  var b2 = JXG.JSXGraph.initBoard('box2', {axis:true,originX: 250, originY: 250, unitX: 25, unitY: 25});
 
  var k = b2.createElement('slider', [[1,8],[5,8],[0,1,4]]);
 
  var k = b2.createElement('slider', [[1,8],[5,8],[0,1,4]]);
  var c = b2.createElement('curve', [function(phi){return Math.cos(2.0*phi); }, [0, 0],0, 2*Math.PI],
+
  var c = b2.createElement('curve', [function(phi){return k.Value()*Math.cos(2.0*phi); }, [0, 0],0, 1*Math.PI],
 
             {curveType:'polar', strokewidth:4});       
 
             {curveType:'polar', strokewidth:4});       
 
</jsxgraph>
 
</jsxgraph>

Revision as of 16:07, 18 March 2009

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

[math]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.createElement('slider', [[1,8],[5,8],[0,1,4]]);
 var c = b1.createElement('curve', [function(phi){return Math.sqrt(k.Value()/phi); }, [0, 0],0, 8*Math.PI],
             {curveType:'polar', strokewidth:4});      
</jsxgraph>


External links