L = 4;
nu = (2.*pi)./L;

x = [ -3.1 9.9 6.5 -8.3 ];

res = [ 0 0 0 ];

for p=0:2
   sum = 0;

   for k=0:(L-1)
     sum = sum + (x(k+1).*exp(-1i.*p.*k.*nu));
   end

   sum = sum ./ L;

   res(p+1) = sum;
end

disp("U1 = ");
disp(res(1));

disp("U2 = ");
disp((x(1)-res(1)-res(3))./cos(angle(res(2))));

disp("U3 = ");
disp(res(3));

disp("phi = ");
disp(angle(res(2)));