procedure TTEST(DATA1:array of real; N1:integer; DATA2:array of real;
                                            N2:integer;var T, PROB:real);
var
    AVE1,AVE2,VAR2,VAR1,DF:real; 
begin 
    AVEVAR(DATA1, N1, AVE1, VAR1);
    AVEVAR(DATA2, N2, AVE2, VAR2);
    DF:=N1 + N2 - 2;
    VAR2:=((N1 - 1) * VAR1 + (N2 - 1) * VAR2) / DF;
    T:=(AVE1 - AVE2) / Sqrt(VAR2 * (1  / N1 + 1  / N2));
    PROB:=BETAI(0.5 * DF, 0.5, DF / (DF + T*T));
end;