Cubic spline interpolation

Constructs a cubic spline through given points. Points can be added by clicking on "Add point".

References

• http://en.wikipedia.org/wiki/Spline_interpolation

The underlying JavaScript code

        board = JXG.JSXGraph.initBoard('box', {originX: 250, originY: 250, unitX: 50, unitY: 25});
        // Axes
        b1axisx = board.createElement('axis', [[0,0], [1,0]], {});
        b1axisy = board.createElement('axis', [[0,0], [0,1]], {});

        var p = [];
        p[0] = board.createElement('point', [-1,2], {style:6});
        p[1] = board.createElement('point', [0,-1], {style:6});
        p[2] = board.createElement('point', [1,0], {style:6});
        p[3] = board.createElement('point', [2,1], {style:6});

        var c = board.createElement('spline', p, {strokeWidth:3});

        var g = board.createElement('glider', [1.5,0,c], {name:'',style:8});
        var t = board.createElement('tangent', [g], {dash:2,strokeColor:'#aa0000'});

        function addPoint() {
          p.push(board.createElement('point',[(Math.random()-0.5)*10,(Math.random()-0.5)*3],{style:6}));
          board.update();
        }