How to adjust the legend for a variable number of plots?

In each figure I have a variable number of plots. However, in the legend I have all the plots. For instance, in the very first figure, I would want only one plot. How can I adjust this?

clc;
clear all;
a=[1/2,1/3,1/4];
l=-0.1:.05:.1;

p = @(x,a,l) 1/3.*(exp(x.^(a))-1)./(exp(x.^(a))+1) + l;

x=linspace(0,.2,101);

for k2 = 1:length(l)
figure(k2)
for k1 = 1:length(a)
    plot(x, p(x,a(k1),l(k2)))
    hold all
    ar{k1} = sprintf('a = %s',rats(a(k1),3));
end
grid
axis([0 .21 0 .25])
hold off
legend(ar, 'Location','best')
end

Answer 1

[Image Analyst]

You need to check if any p are greater than 0. Those elements < 0 would be not shown since you've set the min y value to 0.

clc;
clear all;
a=[1/2,1/3,1/4];
l=-0.1:.05:.1;

p = @(x,a,l) 1/3.*(exp(x.^(a))-1)./(exp(x.^(a))+1) + l;

x=linspace(0,.2,101);

for k2 = 1:length(l)
  figure(k2)
  legendCounter = 1;
  for k1 = 1:length(a)
    pValues = p(x,a(k1),l(k2));
    plot(x, pValues)
    drawnow;
    hold all
    if any(pValues >= 0)
      ar{legendCounter} = sprintf('a = %s',rats(a(k1),3));
      legendCounter = legendCounter + 1;
    end
  end
  grid
  axis([0 .21 0 .25])
  hold off
  legend(ar, 'Location','best')
end

You need to make the colors match for the legend and the plot. It's getting later here so I'll let you do that.

[John]

Thanks. Just moving things around this way must do it:

clc;
clear all;

a=[1/2,1/3,1/4];
l=-0.1:.05:.1;

p = @(x,a,l) 1/3.*(exp(x.^(a))-1)./(exp(x.^(a))+1) + l;

x=linspace(0,.2,101);

for k2 = 1:length(l)
  figure(k2)
  legendCounter = 1;
  for k1 = 1:length(a)
    pValues = p(x,a(k1),l(k2));
    if any(pValues >= 0)
        plot(x, pValues)
    drawnow;
    hold all
      ar{legendCounter} = sprintf('a = %s',rats(a(k1),3));
      legendCounter = legendCounter + 1;
    end
  end
  grid
  axis([0 .21 0 .25])
  hold off
  legend(ar, 'Location','best')
end

[Image Analyst]

Not sure what that did, other than mess up the indenting, but whatever...as long as it works. Thanks for Accepting.

[John]

The indentation got messy, but now it plots if positive. So those that do not show up in the positive quadrant do not get plotted and hence do not appear at the legend.

[Image Analyst]

Oh, I see now. You moved the plot inside the if. I guess that's more efficient. I just didn't notice because you set up the axis limits so that negative parts don't show up anyway. By the way, what I always do before posting is to type control-a, control-i in the MATLAB editor to fix the indenting before pasting it here.