Fermat's spiral: Difference between revisions
From JSXGraph Wiki
A WASSERMANN (talk | contribs) No edit summary |
A WASSERMANN (talk | contribs) No edit summary |
||
| Line 4: | Line 4: | ||
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', {originX: 250, originY: 250, unitX: 25, unitY: 25}); | |||
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', {originX: 250, originY: 250, unitX: 25, unitY: 25}); | ||
var a = board. | var a = board.create('slider', [[1,9],[5,9],[0,1,4]],{name:'a'}); | ||
var c1 = board. | var c1 = 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}); | ||
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]] | ||
Revision as of 20:57, 29 September 2010
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', {originX: 250, originY: 250, unitX: 25, unitY: 25});
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});
