Difference between revisions of "Polynomial regression I"

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===The underlying JavaScript code===
 
===The underlying JavaScript code===
<source lang="xml">
+
<source lang="javascript">
<jsxgraph width="700" height="500">
 
 
var data = "406.60 428.50 429.30 426.30 434.70 415.90 ... many points ... 521.80 524.40 526.80";
 
var data = "406.60 428.50 429.30 426.30 434.70 415.90 ... many points ... 521.80 524.40 526.80";
 
data = data.split(' ');
 
data = data.split(' ');
Line 64: Line 63:
 
             {strokeColor:'black',fontSize:'14px'});     
 
             {strokeColor:'black',fontSize:'14px'});     
 
brd.unsuspendUpdate();
 
brd.unsuspendUpdate();
</jsxgraph>
 
 
</source>
 
</source>
  
 
[[Category:Examples]]
 
[[Category:Examples]]

Revision as of 12:47, 8 June 2011

Through the points defining the dashed line the regression polynomial of degree 'degree' is computed and displayed. The points can be scaled by adjusting the slider 'scale'. The degree of the regression polynomial can be changed by using the slider 'degree'.

The underlying JavaScript code

var data = "406.60 428.50 429.30 426.30 434.70 415.90 ... many points ... 521.80 524.40 526.80";
data = data.split(' ');
var datax = [];
for (i = 0; i < data.length; i++)  { 
    data[i] = (parseFloat(data[i])-450.0); 
    datax[i] = i;
}
    
var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2, 100, data.length+2, -70], grid: false, axis:true});
brd.suspendUpdate();
var s = brd.create('slider',[[10,70],[80,70],[0,1,1]],{name:'scale'});     
var deg = brd.create('slider',[[10,90],[80,90],[1,1,10]],{name:'degree',snapWidth:1});     
var curve = brd.create('curve',[[],[]],{strokeColor:'gray',dash:2});     
curve.updateDataArray = function() {
    var i, len = data.length;
    this.dataX = datax.slice(0,len); 
    for(i=0;i<len;i++) this.dataY[i] = s.Value()*data[i]; 
}
var regressionPolynomial = JXG.Math.Numerics.regressionPolynomial(deg,datax,curve.dataY);

var reg = brd.create('functiongraph',[regressionPolynomial],{strokeColor:'black'});     
brd.create('glider',[100,30,reg],{strokeColor:'black'});     

t = brd.create('text',[20,40,
            function(){ return "r(x) = " + regressionPolynomial.getTerm();}
            ],
            {strokeColor:'black',fontSize:'14px'});     
brd.unsuspendUpdate();