Modjular

/**
 * At least two points are needed to interpolate something.
 * @class Lagrange polynomial interpolation.
 * The computed interpolation polynomial will be reffered to as L(x).
 * @example
 * var l = new Lagrange(0, 0, 1, 1);
 * var index = l.addPoint(0.5, 0.8);
 * console.log(l.valueOf(0.1));
 * 
 * l.changePoint(index, 0.5, 0.1);