procedure VANDER(X:array of real;var W:array of real;
                                 Q:array of real; N:integer);
const
    NMAX = 100;    ZERO = 0;
    ONE = 1;
var
    C:array[0..100] of real;
    I,J,K,K1:integer; XX,T,B,S:real;
begin
    If N = 1 Then
        W[1]:=Q[1]
    Else
    begin
        For I:=1 To N do
            C[I]:=ZERO;
        C[N]:=-X[1];
        For I:=2 To N do
        begin
            XX:=-X[I];
            For J:=N + 1 - I To N - 1 do
                C[J]:=C[J] + XX * C[J + 1];
            C[N]:=C[N] + XX;
        end;
        For I:=1 To N do
        begin
            XX:=X[I];
            T:=ONE;
            B:=ONE;
            S:=Q[N];
            K:=N;
            For J:=2 To N do
            begin
                K1:=K - 1;
                B:=C[K] + XX * B;
                S:=S + Q[K1] * B;
                T:=XX * T + B;
                K:=K1;
            end;
            W[I]:=S / T;
        end;
    end;
end;