quintic fit {-1,0},{-0.83,0.00005},{-0.67,0.00254},{-0.5,0.02875},{-0.33,0.11532},{-0.17,0.28271},{0,0.50162},{0.17,0.71822},{0.33,0.88384},{0.5,0.97016},{0.67,0.99711},{0.83,0.99989},{1,1}