Fermat's spiral: Difference between revisions
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with a real number <math>a</math>. | with a real number <math>a</math>. | ||
<jsxgraph width="500" height="500"> | <jsxgraph width="500" height="500"> | ||
var board = JXG.JSXGraph.initBoard('jxgbox', { | var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-10, 10, 10, -10]}); | ||
var a = board.create('slider', [[1,9],[5,9],[0,1,4]],{name:'a'}); | var a = board.create('slider', [[1,9],[5,9],[0,1,4]],{name:'a'}); | ||
var c1 = board.create('curve', [function(phi){return a.Value()*Math.sqrt(phi); }, [0, 0],0, 8*Math.PI], | var c1 = board.create('curve', [function(phi){return a.Value()*Math.sqrt(phi); }, [0, 0],0, 8*Math.PI], | ||
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===The JavaScript code to produce this picture=== | ===The JavaScript code to produce this picture=== | ||
<source lang="javascript"> | <source lang="javascript"> | ||
var board = JXG.JSXGraph.initBoard('jxgbox', { | var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-10, 10, 10, -10]}); | ||
var a = board.create('slider', [[1,9],[5,9],[0,1,4]],{name:'a'}); | var a = board.create('slider', [[1,9],[5,9],[0,1,4]],{name:'a'}); | ||
var c1 = board.create('curve', [function(phi){return a.Value()*Math.sqrt(phi); }, [0, 0],0, 8*Math.PI], | var c1 = board.create('curve', [function(phi){return a.Value()*Math.sqrt(phi); }, [0, 0],0, 8*Math.PI], | ||
Latest revision as of 14:11, 7 June 2011
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
var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-10, 10, 10, -10]});
var a = board.create('slider', [[1,9],[5,9],[0,1,4]],{name:'a'});
var c1 = board.create('curve', [function(phi){return a.Value()*Math.sqrt(phi); }, [0, 0],0, 8*Math.PI],
{curveType:'polar', strokewidth:4});
var c2 = board.create('curve', [function(phi){return -a.Value()*Math.sqrt(phi); }, [0, 0],0, 8*Math.PI],
{curveType:'polar', strokewidth:4});
