Polynomial regression I: Difference between revisions

From JSXGraph Wiki
No edit summary
No edit summary
Line 12: Line 12:
      
      
var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2, 100, data.length+2, -70], grid: false, axis:true});
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 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 deg = brd.create('slider',[[10,90],[80,90],[1,1,10]],{name:'degree',snapWidth:1});     
Line 22: Line 23:
var regressionPolynomial = JXG.Math.Numerics.regressionPolynomial(deg,datax,curve.dataY);
var regressionPolynomial = JXG.Math.Numerics.regressionPolynomial(deg,datax,curve.dataY);


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


t = brd.create('text',[20,40,
t = brd.create('text',[20,40,
Line 31: Line 30:
             ],
             ],
             {strokeColor:'black',fontSize:'14px'});     
             {strokeColor:'black',fontSize:'14px'});     
brd.unsuspendUpdate();
</jsxgraph>
</jsxgraph>



Revision as of 14:12, 29 September 2010

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

<jsxgraph width="700" height="500">

    data = "406.60 428.50 429.30 426.30 434.70 415.90 ... many points ... 521.80 524.40 526.80";
    data = data.split(' ');
    datax = [];
    for (i = 0; i < data.length; i++)  { 
        data[i] = (parseFloat(data[i])-450.0); 
        datax[i] = i;
        }
    

brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2, 100, data.length+2, -70], grid: false, axis:true});
s = brd.createElement('slider',[[10,70],[80,70],[0,1,1]],{name:'scale'});     
deg = brd.createElement('slider',[[10,90],[80,90],[1,1,10]],{name:'degree',snapWidth:1});     
curve = brd.createElement('curve',[datax,[]],{strokeColor:'gray',dash:2});     
curve.updateDataArray = function() {
    var i, len = data.length;
    for(i=0;i<len;i++) { this.dataY[i] = s.Value()*data[i]; }
}
regressionPolynomial = JXG.Math.Numerics.regressionPolynomial(deg,datax,curve.dataY);  // generateFunction();

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

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

</jsxgraph>