Draggable exponential function: Difference between revisions

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<jsxgraph width="400" height="400" box="box1">
<jsxgraph width="400" height="400" box="box1">
var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 20, 5, -1], axis:true});
var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 20, 5, -2], axis:true});


var A = board.create('point', [1, Math.exp(1)]);
var A = board.create('point', [1, Math.exp(1)]);
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           }], {fontSize: 16});
           }], {fontSize: 16});
</jsxgraph>
</jsxgraph>
 
<html>
<input type="button" onClick="alert('a = ' + (Math.log(A.Y()) / A.X()).toFixed(2))" value="Show value of a" />
</html>


===The JavaScript code===
===The JavaScript code===
<source lang="javascript">
<source lang="javascript">
var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 20, 5, -1], axis:true});
var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 20, 5, -2], axis:true});


var A = board.create('point', [1, Math.exp(1)]);
var A = board.create('point', [1, Math.exp(1)]);
Line 36: 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="html4strict">
<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]]

Latest revision as of 09:41, 16 February 2016

Plot the function

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

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

That means,

[math]\displaystyle{ 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" />