Multiple Plots in One Iterative Script

I am trying to plot two graphs in this iterative process. Thanks in advance.

function BisectMeth(xL, xU, es, itermax)
f = @(x)exp(-x)-x;
xR = xU;
fL = f(xL);
for iter = [1:itermax]
    xRold = xR;
    xR = (xL +xU)/2;
    fR = f(xR);
    if xR ~= 0
        ea = abs((xR-xRold)/xR)*100;
    end
    check = fL*fR;
    if check <0
        xU = xR;
      
    else
        if check > 0
            xL = xR;
            fL = fR;
        else 
            ea = 0;
        end
   
    end
    if ea < es 
        break
    end
    if iter == itermax && ea > es
        disp('Max # of iterations reached before acheiving prescribes tolerance')
    end
    iter = [0:itermax]
 AppErr = (xR*ea)/100;
 TrueErr = 0.56714329 - xR;
 
 figure(1);
 plot(iter,TrueErr);
 xlabel('Number of Iterations');
 ylabel('True Error');
 
 figure(2);
 plot(iter, AppErr);
 xlabel('Number of Iterations');
 ylabel('Approximate Error');
end

fprintf('Root is %f\n', xR)
fprintf('Approximate error is %f\n',AppErr)
fprintf('True error is %f\n', TrueErr)
end

Answer 1

[Bjorn Gustavsson]

If you want all the points for each iteration in the 2 figures, then you will have to insert a hold on after each plotting command:

 figure(1);
 plot(iter,TrueErr,'.');
 hold on
 xlabel('Number of Iterations');
 ylabel('True Error');
 
 figure(2);
 plot(iter, AppErr,'.');
 hold on
 xlabel('Number of Iterations');
 ylabel('Approximate Error');

You might also have to set:

 axis auto

This is if you want to see how the iteration proceeds, which is sometimes convenient/soothing/necessary/interesting.

But this is a clumsy way to go about this if you only want to see how the iteration process worked after it finished. For this case it is better to store away everyting you want to look at in arrays and plot everyting after the end of the iteration. Perhaps something like:

  AppErr = (xR*ea)/100;
 TrueErr = 0.56714329 - xR;
 TruErrAll(iter) = Truerr;
  AppErrAll(iter) = (xR*ea)/100;

 end
 figure(1);
 plot(TrueErrAll);
 xlabel('Number of Iterations');
 ylabel('True Error');
 
 figure(2);
 plot(AppErrAll);
 xlabel('Number of Iterations');
 ylabel('Approximate Error');

I bloody well hope I guessed close enough...

HTH