Polynomial regression I: Difference between revisions
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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}); | ||
var curve = brd.create('curve',[ | var curve = brd.create('curve',[[],[]],{strokeColor:'gray',dash:2}); | ||
curve.updateDataArray = function() { | curve.updateDataArray = function() { | ||
var i, len = data.length; | var i, len = data.length; | ||
for(i=0;i<len;i++) | this.dataX = datax.slice(0,len); } | ||
for(i=0;i<len;i++) this.dataY[i] = s.Value()*data[i]; | |||
} | } | ||
brd.update(); | brd.update(); | ||
Revision as of 21:33, 8 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>
