Fermat's spiral: Difference between revisions

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(New page: It can be described in polar coordinates <math>(r, \theta)</math> by the equation :<math>r = \pm a\theta^{1/2}\,</math> with a real number <math>a</math>. <html> <link rel="stylesheet" t...)
 
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Line 28: Line 28:
  board = JXG.JSXGraph.initBoard('jsxgbox', {originX: 250, originY: 250, unitX: 50, unitY: 50});
  board = JXG.JSXGraph.initBoard('jsxgbox', {originX: 250, originY: 250, unitX: 50, unitY: 50});
  var a = board.createElement('slider', [[1,-1],[5,-1],[0,1,4]]);
  var a = board.createElement('slider', [[1,-1],[5,-1],[0,1,4]]);
  var b = board.createElement('slider', [[1,-2],[5,-2],[0,0-25,4]]);
  var c1 = board.createElement('curve', [function(phi){return a.Value()*Math.sqrt(phi); }, [0, 0],'phi',0, 8*Math.PI],
  var c = board.createElement('curve', [function(phi) a.Value()+b.Value()*phi; }, [0, 0],'phi',0, 8*Math.PI],
            {curveType:'polar', strokewidth:4});      
  var c2 = board.createElement('curve', [function(phi){return -a.Value()*Math.sqrt(phi); }, [0, 0],'phi',0, 8*Math.PI],
             {curveType:'polar', strokewidth:4});         
             {curveType:'polar', strokewidth:4});         
</source>
</source>

Revision as of 17:20, 10 February 2009

It can be described in polar coordinates [math]\displaystyle{ (r, \theta) }[/math] by the equation

[math]\displaystyle{ r = \pm a\theta^{1/2}\, }[/math]

with a real number [math]\displaystyle{ a }[/math].

The JavaScript code to produce this picture

<link rel="stylesheet" type="text/css" href="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraph.css" />
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/prototype.js"></script>
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraphcore.js"></script>
<div id="jsxgbox" class="jxgbox" style="width:500px; height:500px;"></div>
 board = JXG.JSXGraph.initBoard('jsxgbox', {originX: 250, originY: 250, unitX: 50, unitY: 50});
 var a = board.createElement('slider', [[1,-1],[5,-1],[0,1,4]]);
 var c1 = board.createElement('curve', [function(phi){return a.Value()*Math.sqrt(phi); }, [0, 0],'phi',0, 8*Math.PI],
             {curveType:'polar', strokewidth:4});        
 var c2 = board.createElement('curve', [function(phi){return -a.Value()*Math.sqrt(phi); }, [0, 0],'phi',0, 8*Math.PI],
             {curveType:'polar', strokewidth:4});