# Difference between revisions of "Lagrange interpolation"

From JSXGraph Wiki

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</html> | </html> | ||

<jsxgraph box="box" width="600" height="400"> | <jsxgraph box="box" width="600" height="400"> | ||

− | board = JXG.JSXGraph.initBoard('box', {boundingbox: [-5, 10, 7, -6], axis: true}); | + | var board = JXG.JSXGraph.initBoard('box', {boundingbox: [-5, 10, 7, -6], axis: true}); |

var p = []; | var p = []; | ||

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=== The underlying JavaScript code === | === The underlying JavaScript code === | ||

<source lang="javascript"> | <source lang="javascript"> | ||

− | board = JXG.JSXGraph.initBoard('box', {boundingbox: [-5, 10, 7, -6], axis: true}); | + | var board = JXG.JSXGraph.initBoard('box', {boundingbox: [-5, 10, 7, -6], axis: true}); |

var p = []; | var p = []; |

## Revision as of 10:08, 8 June 2011

Constructs a polynomial of degree [math]n[/math] through [math]n+1[/math] given points. Points can be added by clicking on "Add point". The dotted line is the graph of the first derivative, the dashed line is the graph of the second derivative.

### References

### The underlying JavaScript code

```
var board = JXG.JSXGraph.initBoard('box', {boundingbox: [-5, 10, 7, -6], axis: true});
var p = [];
p[0] = board.create('point', [-1,2], {size:4});
p[1] = board.create('point', [3,-1], {size:4});
var f = board.lagrangePolynomial(p);
var graph = board.create('functiongraph', [f,-10, 10], {strokeWidth:3});
var d1 = board.create('functiongraph', [board.D(f), -10, 10], {dash:1});
var d2 = board.create('functiongraph', [board.D(board.D(f)), -10, 10], {dash:2});
function addPoint() {
p.push(board.create('point',[(Math.random()-0.5)*10,(Math.random()-0.5)*3],{size:4}));
board.update();
}
```