> F[1]:=(1-xi)*xi/2-4*sin(Pi*xi)/Pi^3;

                          (1 - xi) xi   4 sin(Pi xi)
                  F[1] := ----------- - ------------
                               2              3
                                            Pi

> F[2]:=(1-xi)*xi/2-1/2*sin(Pi*xi)/Pi;

                         (1 - xi) xi       sin(Pi xi)
                 F[2] := ----------- - 1/2 ----------
                              2                Pi

> F[3]:=(1-xi)*xi/2-sin(Pi*xi)/Pi^2;

                           (1 - xi) xi   sin(Pi xi)
                   F[3] := ----------- - ----------
                                2             2
                                            Pi

> F[4]:=(1-xi)*xi/2-1/8*sin(Pi*xi);

                         (1 - xi) xi
                 F[4] := ----------- - 1/8 sin(Pi xi)
                              2

> plot({F[1],F[2],F[3],F[4]},xi= 0..0.5, numpoints=24);

> 
> 
