x_i             f_i          fit (M=3)   approximating function

-1.000000       -0.260052       -0.365502       -0.295552
-0.900000       -0.142449       -0.126021       -0.154827
-0.800000        0.002508        0.088252       -0.001304
-0.600000        0.339986        0.441172        0.339772
-0.400000        0.671133        0.693258        0.671129
-0.200000        0.912005        0.844509        0.912005
 0.000000        1.000000        0.894926        1.000000
 0.200000        0.912005        0.844509        0.912005
 0.400000        0.671133        0.693258        0.671129
 0.600000        0.339986        0.441172        0.339772
 0.800000        0.002508        0.088252       -0.001304
 0.900000       -0.142449       -0.126021       -0.154827
 1.000000       -0.260052       -0.365502       -0.295552