Difference between revisions of "Polynomial regression I"

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Line 14: Line 14:
  
 
brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2, 100, data.length+2, -70], grid: false, axis:true});
 
brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2, 100, data.length+2, -70], grid: false, axis:true});
s = brd.createElement('slider',[[10,70],[100,70],[0,1,1]],{name:'scale'});     
+
s = brd.createElement('slider',[[10,70],[80,70],[0,1,1]],{name:'scale'});     
deg = brd.createElement('slider',[[10,90],[100,90],[1,1,10]],{name:'degree',snapWidth:1});     
+
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 = brd.createElement('curve',[datax,[]],{strokeColor:'gray',dash:2});     
 
curve.updateDataArray = function() {
 
curve.updateDataArray = function() {
Line 47: Line 47:
  
 
brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2, 100, data.length+2, -70], grid: false, axis:true});
 
brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-2, 100, data.length+2, -70], grid: false, axis:true});
s = brd.createElement('slider',[[10,70],[100,70],[0,1,1]],{name:'scale'});     
+
s = brd.createElement('slider',[[10,70],[80,70],[0,1,1]],{name:'scale'});     
deg = brd.createElement('slider',[[10,90],[100,90],[1,1,10]],{name:'degree',snapWidth:1});     
+
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 = brd.createElement('curve',[datax,[]],{strokeColor:'gray',dash:2});     
 
curve.updateDataArray = function() {
 
curve.updateDataArray = function() {

Revision as of 15:05, 24 September 2009

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>