function fLb: Real; //Двоичный логарифм
    var_input 
        X:real;
    end_var
    var
        s:real:=0.0;
        a:real:=0.5;
        i:udint;
        b:real;


    end_var

//PRG

if X>0 then
    if X>=1 then
        b:=1;
        X:=X;
    else
        b:=-1;
        X:=1/X;
    end_if


    if x>2 then
        s:=udint_to_real( cd32(real_to_udint(x)));
        X:=X/ pow(2,s);
    end_if;

    for i:=0 to 16 do
        x:=x*x;
        if x>2 then
            x:=x/2;
            s:=s+a;
        end_if;
        a:=a*0.5;
    end_for
    fLb:=s*b;
end_if

end_function