This programm will find the Lagrange polynomial of degree 3 passing though 4 points. You can place the 4 points A B C and D anywhere (the only rule is that two points can't have the same X-value) and click on the "Find Polynomial" Button. A curve will then be drawn going though each point. Ce programme permet de trouver le polynome de Lagrange passant par 4 points choisis. Placez les points où vous voulez et cliquez sur le boutton "Find Polynomial" pour voir la la courbe passer à travers vos points.
If interested: http://mathworld.wolfram.com/LagrangeInterpolatingPolynomial.html