Inverse Composition Rules: Difference between revisions
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<form name="input">  | <form name="input">  | ||
<table>  | <table>  | ||
  <tr>  |   <tr style="color:blue">  | ||
    <th>f(x)</th>  |     <th>f(x)</th>  | ||
    <td>sin(x)</td>  |     <td>sin(x)</td>  | ||
Revision as of 13:48, 19 June 2009
The underlying JavaScript code
<html>
<form name="input">
<table>
 <tr>
   <th>f(x)</th>
   <td>sin(x)</td>
   <td>cos(x)</td>
   <td>tan(x)</td>
   <td>x<sup>2</sup></td>
   <td>sinh(x)</td>
   <td>exp(x)</td>
 </tr>
 <tr>
   <td> </td>
   <td><input type="radio" name="f" value="sin" checked onChange="change(this)"></td>
   <td><input type="radio" name="f" value="cos"         onChange="change(this)"></td>
   <td><input type="radio" name="f" value="tan"         onChange="change(this)"></td>
   <td><input type="radio" name="f" value="square"      onChange="change(this)"></td>
   <td><input type="radio" name="f" value="sinh"        onChange="change(this)"></td>
   <td><input type="radio" name="f" value="exp"         onChange="change(this)"></td>
 </tr>
 <tr>
   <th>g(x)</th>
   <td>arcsin(x)</td>
   <td>arccos(x)</td>
   <td>arctan(x)</td>
   <td>√(x)</td>
   <td>arcsinh(x)</td>
   <td>log(x)</td>
 </tr>
 <tr>
   <td> </td>
   <td><input type="radio" name="g" value="asin" checked onChange="change(this)"></td>
   <td><input type="radio" name="g" value="acos"         onChange="change(this)"></td>
   <td><input type="radio" name="g" value="atan"         onChange="change(this)"></td>
   <td><input type="radio" name="g" value="sqrt"         onChange="change(this)"></td>
   <td><input type="radio" name="g" value="asinh"        onChange="change(this)"></td>
   <td><input type="radio" name="g" value="log"          onChange="change(this)"></td>
 </tr>
 <tr>
   <th>Composition</th>
   <td>f(g(x)</td>
   <td>g(f(x)</td>
   <td> </td>
   <td> </td>
   <td> </td>
   <td> </td>
 </tr>
 <tr>
   <td> </td>
   <td><input type="radio" name="fg" value="fg" checked onChange="comp(this)"></td>
   <td><input type="radio" name="fg" value="gf"         onChange="comp(this)"></td>
   <td> </td>
   <td> </td>
   <td> </td>
   <td> </td>
 </tr>
</table>
</form>
</html>
<jsxgraph width="600" height="600" box="box">
var brd = JXG.JSXGraph.initBoard('box', {axis:true, originX: 300, originY: 300, grid:true, unitX: 100, unitY: 100});
var f, g, fg;
var change = function(obj) {
 var t = obj.value; 
 if (t=='sin')           { f = function(x) { return Math.sin(x); } 
 } else if (t=='cos')    { f = function(x) { return Math.cos(x); }
 } else if (t=='tan')    { f = function(x) { return Math.tan(x); }
 } else if (t=='square') { f = function(x) { return x*x; }
 } else if (t=='sinh')   { f = function(x) { return brd.sinh(x); }
 } else if (t=='exp')    { f = function(x) { return Math.exp(x); }
 } else if (t=='asin')   { g = function(x) { return Math.asin(x); }
 } else if (t=='acos')   { g = function(x) { return Math.acos(x); }
 } else if (t=='atan')   { g = function(x) { return Math.atan(x); }
 } else if (t=='sqrt')   { g = function(x) { return Math.sqrt(x); }
 } else if (t=='asinh')  { g = function(x) { return Math.log(x+Math.sqrt(1+x*x)); }
 } else if (t=='log')    { g = function(x) { return Math.log(x); }
 }
 plotf.Y = f; plotf.updateCurve();
 plotg.Y = g; plotg.updateCurve();
 brd.update();
}
var comp = function(obj) {
 var t = obj.value; 
 if (t=='fg')           { fg = function(x) { return f(g(x)); } 
 } else if (t=='gf')    { fg = function(x) { return g(f(x)); }
 }
 plotfg.Y = fg; plotfg.updateCurve();
 brd.update();
}
f = function(x) { return Math.sin(x); }
g = function(x) { return Math.asin(x); }
fg = function(x) { return Math.sin(Math.asin(x)); }
plotf = brd.createElement('functiongraph',[f,-2,2],{dash:2});
plotg = brd.createElement('functiongraph',[g,-2,2],{dash:3, strokeColor:'black'});
plotfg = brd.createElement('functiongraph',[fg,-2,2],{strokeColor:'red'});
</jsxgraph>