Problem using hold all

Hi,

I have a while loop in matlab where I am updating some variables and vectors (I have ommited that part from the code because it isn't relevant for this issue). I would like to have a plot with the the values of these variables and vectors between iterations. I have the following code:

 j=0;
 while j<=Niter
    (...) 
    figure(1); subplot(1,2,1); plot(tspan,H_v_c); hold all; subplot(1,2,2); stem(j,J_new); hold all;
    figure(2); 
    subplot(1,2,1); plot(tspan,xout(:,1)+xout(:,2),'r',tspan,xout(:,3),'g',tspan,xout(:,4),'b',tspan,xout(:,5),'c');
    subplot(1,2,2); plot(tspan,v_chemo); hold all;
    j=j+1;
end

However some of the values of J_new from figure(1) subplot(1,2,2) appear in figure(2) subplot(1,2,2). Is there something that I can do to avoid this?

Answer 1

[Jan]

It is safer and in my opinion easier to specify the parents explicitly:

Fig1    = figure;
Axes1_1 = subplot(1,2,1, 'Parent', Fig1, 'NextPlot', 'add');  % Equivalent to: hold on
Axes1_2 = subplot(1,2,2, 'Parent', Fig1, 'NextPlot', 'add');
Fig2    = figure(2); 
Axes2_1 = subplot(1,2,1, 'Parent', Fig2, 'NextPlot', 'add');
Axes2_2 = subplot(1,2,2, 'Parent', Fig2, 'NextPlot', 'add');

j=0;
while j<=Niter   % A FOR loop might be nicer
  (...) 
  plot(tspan,H_v_c, 'Parent', Axes1_1);
  stem(j,J_new, 'Parent', Axes1_2);
  plot(tspan, xout(:,1)+xout(:,2), 'r', 'Parent', Axes2_1);
  plot(tspan, xout(:,3), 'g', 'Parent', Axes2_1);
  plot(tspan, xout(:,4), 'b', 'Parent', Axes2_1);
  plot(tspan, xout(:,5), 'c', 'Parent', Axes2_1);
  plot(tspan, v_chemo, 'Parent', Axes2_2);
  j=j+1;
end

Note that in modern Matlab versions (HG2, 2014b) this is safe also to define the parent:

plot(Axes2_2, ...)

This should be faster also, because it avoids the switching of the active figures and axes.

[Elisa Pacheco]

Thank you so much, Jan Simon. I'll try it. Concerning the for loop, I can't use it because in my code (this was a simpler version) I also evaluate some booleans.