using end value in next iteration

want the Vo at the end of each loop to be used in the start of the next iteration, just can't get to work, I display Vn but its not updating from iteration to iteration. Any thoughts?

    %
    Voo = [30 15 13 10];   %
    while true
    %
    Vo = Voo;
    %
    f1 = 64 / Re1;
    f2 = 64 / Re2;
    f3 = 64 / Re3;
    f4 = 64 / Re4;

    X = [matrix]
    %
    Y = [matrix]
    Vn = X\Y;
    disp(Vn)
    %
    for i = 1:4
        Va(i) = (alpha * Vn(i)) + ((1-alpha) * Vo(i));
        Vo(i) = Va(i);
        if (abs(Va(1)-Vn(1)))<1e-3 
       break;
        end
    end

Answer 1

[Azzi Abdelmalek]

Voo = [30 15 13 10]; 
Vo=Voo
while ~all([Va==Vo,Vo==Vn]) (needs to be approx equal to)
  Vo=Voo
  Re1 = (D(1).*Vo(1)) / nu;
  Re2 = (D(2).*Vo(2)) / nu;
  Re3 = (D(3).*Vo(3)) / nu;
  Re4 = (D(4).*Vo(4)) / nu;
  A = [Matrix];
  b = [Matrix];
  Vn = A\b;% solves four unknowns at A\b % (1 col, 4 rows)
  for i = 1:4
      Va(i) = (alpha * Vn(i)) + ((1-alpha) * Vo(i)); %(1 col, 4 rows)
      Vo(i) = Va(i); %Used as Vo for each in next iteration. (1 col, 4 rows)
  end
end

[harley]

thanks Azzi amended code shown above, i get an error, how do i fix this?

??? Undefined function or variable 'Va'.

while ~all([Va==Vo,Vo==Vn])

[Azzi Abdelmalek]

What is Va?

[harley]

i calculate a new Va with each iteration through Vo, Va calc is 5 lines from the bottom. Not sure how to get around this.

[Azzi Abdelmalek]

you must initialize Va, also what is:

 while ~all([Va==Vo,Vo==Vn])

[harley]

i want it to iterate until Va, Vo and Vn converge , so that part needs to be re-written to allow for some tolerance say 0.01.