Difference between revisions of "Draggable exponential function"

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Line 38: Line 38:
 
           return "a = " + (Math.log(A.Y()) / A.X()).toFixed(2);
 
           return "a = " + (Math.log(A.Y()) / A.X()).toFixed(2);
 
           }], {fontSize: 16});
 
           }], {fontSize: 16});
 +
</source>
 +
 +
<source lang="html">
 +
<input type="button" onClick="alert('a = ' + (Math.log(A.Y()) / A.X()).toFixed(2))" value="Show value of a" />
 
</source>
 
</source>
  
 
[[Category:Examples]]
 
[[Category:Examples]]
 
[[Category:Calculus]]
 
[[Category:Calculus]]

Revision as of 11:40, 16 February 2016

Plot the function

[math] y = e^{ax}[/math]

where the parameter [math]a[/math] is determined by the Point [math]A=(x_A, y_A)[/math].

That means,

[math] a = log(y_A) / x_A [/math]

The JavaScript code

var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 20, 5, -2], axis:true});

var A = board.create('point', [1, Math.exp(1)]);
var graph = board.create('functiongraph', [
         function(x) {
            var a = Math.log(A.Y()) / A.X();
            return Math.exp(a * x);
         }]);
           
var txt = board.create('text', [-3, 10, function () {
           return "a = " + (Math.log(A.Y()) / A.X()).toFixed(2);
          }], {fontSize: 16});
<input type="button" onClick="alert('a = ' + (Math.log(A.Y()) / A.X()).toFixed(2))" value="Show value of a" />