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"> | ||
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], | |||
board = JXG.JSXGraph.initBoard(' | |||
var a = board. | |||
var c1 = board. | |||
{curveType:'polar', strokewidth:4}); | {curveType:'polar', strokewidth:4}); | ||
var c2 = board. | var c2 = board.create('curve', [function(phi){return -a.Value()*Math.sqrt(phi); }, [0, 0],0, 8*Math.PI], | ||
{curveType:'polar', strokewidth:4}); | {curveType:'polar', strokewidth:4}); | ||
</jsxgraph> | |||
</ | |||
===The JavaScript code to produce this picture=== | ===The JavaScript code to produce this picture=== | ||
<source lang="javascript"> | <source lang="javascript"> | ||
board = JXG.JSXGraph.initBoard(' | var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-10, 10, 10, -10]}); | ||
var a = board. | 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 | |||
{curveType:'polar', strokewidth:4}); | {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}); | |||
</source> | </source> | ||
[[Category:Examples]] | [[Category:Examples]] | ||
[[Category:Curves]] | [[Category:Curves]] | ||
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});
