Difference between revisions of "Archimedean spiral"

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Line 15: Line 15:
 
  var c = board.createElement('curve', [function(phi){return a.Value()+b.Value()*phi; }, [0, 0],'phi',0, 8*Math.PI],
 
  var c = board.createElement('curve', [function(phi){return a.Value()+b.Value()*phi; }, [0, 0],'phi',0, 8*Math.PI],
 
             {curveType:'polar', strokewidth:4});       
 
             {curveType:'polar', strokewidth:4});       
var p = board.createElement('glider', [1,1,c], {name:' '});
 
var t = board.createElement('tangent', [p], {dash:1,strokeColor:'red'});
 
 
    
 
    
 
</script>  
 
</script>  

Revision as of 19:38, 10 February 2009

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

[math]\, r=a+b\theta[/math]

with real numbers [math]a[/math] and [math]b[/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 b = board.createElement('slider', [[1,-2],[5,-2],[0,0-25,4]]);
 var c = board.createElement('curve', [function(phi) a.Value()+b.Value()*phi; }, [0, 0],'phi',0, 8*Math.PI],
             {curveType:'polar', strokewidth:4});