Difference between revisions of "Logarithmic spiral"
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| Line 11: | Line 11: | ||
<script language="JavaScript"> | <script language="JavaScript"> | ||
board = JXG.JSXGraph.initBoard('jsxgbox', {originX: 250, originY: 250, unitX: 25, unitY: 25}); | board = JXG.JSXGraph.initBoard('jsxgbox', {originX: 250, originY: 250, unitX: 25, unitY: 25}); | ||
| − | var a = board.createElement('slider', [[1,-1],[5,-1],[0,0. | + | var a = board.createElement('slider', [[1,-1],[5,-1],[0,0.3,1]]); |
| − | var b = board.createElement('slider', [[1,-2],[5,-2],[0,0. | + | var b = board.createElement('slider', [[1,-2],[5,-2],[0,0.15,1]]); |
var c = board.createElement('curve', [function(phi){return a.Value()*board.pow(Math.E,b.Value()*phi); }, [0, 0],'phi',0, 8*Math.PI], | var c = board.createElement('curve', [function(phi){return a.Value()*board.pow(Math.E,b.Value()*phi); }, [0, 0],'phi',0, 8*Math.PI], | ||
{curveType:'polar', strokewidth:4}); | {curveType:'polar', strokewidth:4}); | ||
| Line 26: | Line 26: | ||
<source lang="javascript"> | <source lang="javascript"> | ||
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 | + | var a = board.createElement('slider', [[1,-1],[5,-1],[0,0.3,1]]); |
| − | var b = board.createElement('slider', [[1,-2],[5,-2],[0,0 | + | var b = board.createElement('slider', [[1,-2],[5,-2],[0,0.15,1]]); |
| − | var c = board.createElement('curve', [function(phi) a.Value() | + | var c = board.createElement('curve', [function(phi){return a.Value()*board.pow(Math.E,b.Value()*phi); }, [0, 0],'phi',0, 8*Math.PI], |
{curveType:'polar', strokewidth:4}); | {curveType:'polar', strokewidth:4}); | ||
</source> | </source> | ||
Revision as of 19:26, 10 February 2009
It can be described in polar coordinates [math](r, \theta)[/math] by the equation
- [math]r = ae^{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],[0,0.3,1]]);
var b = board.createElement('slider', [[1,-2],[5,-2],[0,0.15,1]]);
var c = board.createElement('curve', [function(phi){return a.Value()*board.pow(Math.E,b.Value()*phi); }, [0, 0],'phi',0, 8*Math.PI],
{curveType:'polar', strokewidth:4});
