View source for Polar curve plotter

<html>
<p>
  <textarea cols=60 rows=4 id="eingabe">function r(t) {return 0.2*t; };
</textarea><br />
  <input type="button" value="plot" onClick="plot()">
  <input type="button" value="clear all" onClick="clearAll()">
</p>
</html>
<jsxgraph width="500" height="500">
board = JXG.JSXGraph.initBoard('jxgbox', {axis:true, boundingbox:[-5,5,5,-5]});
a = board.createElement('slider', [[0,-1],[3,-1],[-4*Math.PI,0,0]], {style:6, name:'a'});
b = board.createElement('slider', [[0,-2],[3,-2],[0,7,4*Math.PI]], {style:6, name:'b'});
function plot(){
  eval(document.getElementById("eingabe").value);
  graph = board.createElement('curve', [
            r, [0,0], 
            function(){return a.Value();}, 
            function(){return b.Value();}
            ], 
            {curveType:'polar',strokeColor:'red', strokeWidth:2}
          );
  board.update();
} 

function clearAll() { 
  JXG.JSXGraph.freeBoard(board);
  board = JXG.JSXGraph.initBoard('jxgbox', {axis:true, boundingbox: [-5, 5, 5, -5]});
  a = board.createElement('slider', [[0,-1],[3,-1],[-4*Math.PI,0,0]], {style:6, name:'a'});
  b = board.createElement('slider', [[0,-2],[3,-2],[0,7,4*Math.PI]], {style:6, name:'b'});
}

plot();
</jsxgraph>

===The JavaScript code===
<source lang="javascript">
board = JXG.JSXGraph.initBoard('jxgbox', {axis:true, boundingbox:[-5,5,5,-5]});
a = board.createElement('slider', [[0,-1],[3,-1],[-4*Math.PI,0,0]], {style:6, name:'a'});
b = board.createElement('slider', [[0,-2],[3,-2],[0,7,4*Math.PI]], {style:6, name:'b'});
function plot(){
  eval(document.getElementById("eingabe").value);
  graph = board.createElement('curve', [
            r, [0,0], 
            function(){return a.Value();}, 
            function(){return b.Value();}
            ], 
            {curveType:'polar',strokeColor:'red', strokeWidth:2}
          );
  board.update();
} 

function clearAll() { 
  JXG.JSXGraph.freeBoard(board);
  board = JXG.JSXGraph.initBoard('jxgbox', {axis:true, boundingbox: [-5, 5, 5, -5]});
  a = board.createElement('slider', [[0,-1],[3,-1],[-4*Math.PI,0,0]], {style:6, name:'a'});
  b = board.createElement('slider', [[0,-2],[3,-2],[0,7,4*Math.PI]], {style:6, name:'b'});
}

plot();
</source>

[[Category:Examples]]
[[Category:Calculus]]
[[Category:Curves]]