stop the data comprising from 4 different loops in an array

Hi here is the code :

%%%%%%
for w=[0.01,0.1,0.3,0.8,3]
for K=4:9
    for T=2:3
        for tau=1:2
G=K*exp(-(tau*(i*w)))/(T*i*w+1);
G_n=6.5/((2.5*(i*w)+1)*(1.5*(i*w)+1));
Delta_a=G-G_n;
%%%%%%%

I want to have Delta_a consisting from an array covering all the values not the very last one Thanks

[José-Luis]

http://se.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup#answer_18099

Answer 1

[Guillaume]

You could modify your loops in order to create indices for your Delta_a:

w = [0.01,0.1,0.3,0.8,3];
K = 4:9;
T = 2:3;
tau = 1:2;
Delta_a = zeros(numel(w), numel(K), numel(T), numel(tau));  %predeclare array to avoid growing it in the loop
for wi = 1:numel(w)
   for ki = 1:numel(K)
      for ti = 1:numel(T)
         for taui = 1:numel(tau);
            G = K(ki)*exp(-(tau(taui)*(i*w(wi))))/(T(ti)*i*w(wi)+1);
            G_n = 6.5/((2.5*(i*w(wi))+1)*(1.5*(i*w(wi))+1));
            Delta_a(wi, ki, ti, taui) = G-G_n;
         end
      end
   end
end

Or you could just no bother with the loops, and do it all in one go. It's very easy, particularly if you have R2016b:

w = [0.01,0.1,0.3,0.8,3].';     %column vector
K = 4:9;                        %row vector
T = permute(2:3, [1 3 2]);      %vector along 3rd dimension
tau = permute(1:2, [1 4 3 2]);  %vector along 4th dimension
G = K .* exp(-(tau.*1i.*w)) ./ (T.*1i.*w + 1);
G_n = 6.5 ./ ((2.5*1i*w + 1) .* (1.5*1i*w+1));
Delta_a = G - G_n;

Prior to R2016b, you have to use bsxfun:

G = bsxfun(@times, K, exp(-bsxfun(@rdivide, bsxfun(@times, tau, 1i*w), bsxfun(@times, T, 1i*w) + 1)));
G_n = 6.5 ./ ((2.5*1i*w + 1) .* (1.5*1i*w+1));
Delta_a = G - G_n;

Answer 2

[Jan]

wv   = [0.01,0.1,0.3,0.8,3];
Kv   = 4:9;
Tv   = 2:3;
tauv = 1:2;
Delta_a = zeros(numel(wv), numel(Kv), numel(Tv), numel(tauv));  % Pre-allocate
for iw = 1:numel(w)
  w = wv(iw);
  G_n = 6.5/((2.5*(1i*w)+1)*(1.5*(1i*w)+1));  % 1i instead of i
  for iK = 1:numel(Kv)
    K = Kv(iK);
    for iT = 1:numel(Tv)
      T = Tv(iT);
      for itau = 1:numel(tauv)
        tau = tauv(itau);
        G   = K*exp(-(tau*(1i*w)))/(T*1i*w+1);
        Delta_a(iw, iK, iT, itau) = G-G_n;
      end
   end
end

"i" is confuced with the imaginary unit too often, so use 1i instead.