MATLAB Legend title issue

Hi,

I an exectuing the following code to get a graph.

figure
grid
hold on;

for n=1:length(zeta_dom_r)
    if abs(zeta_dom_r(n)-0.000)>0.0001
        A(n)=0;
        B(n)=0;

      end
  end

          plot(A(:), B(:), 'k.-')
     legend('Gain =0', 'Gain =0.05', 'Gain =0.1');

          xlabel('\tau (s)');
          ylabel('T Delay (s)');
          xlim([0 5]);
          ylim([0 0.5]);

I want to give one single title to legend i.e Gain. I do not want to write Gain again for every single line. Kindly let me know how to give title to the legend. I am using Matlab 2015.

[dpb]

It's not easy to find (and I've not used it enough to know the answer specifically otomh), but there's a section in documentation title "Controlling Legends" that will show you what you can control. I think it's possible by making some groupings but in my one foray into the arena I believe I came out bloodied.

It's under Annotation Objects or if you dig far enough down in the legends doc there's eventually a link.

[Walter Roberson]

You are only plotting one thing in this code, but you are supplying 3 legends. If this code is being invoked 3 times then the legend should be built afterwards.

In the code segment you show, should we assume that A and B have been set to values before this code?

It is recommended to switch to logical indexing.

idx = abs(zeta_dom_r) > 0.0001;
A(idx) = 0;
B(idx) = 0;

No loop.

[Waqas Syed]

Thanks dpb. I will look into that.

And Thanks alot Walter. I knew that my programming technique was somehow inefficient.

And yes, A & B have been set to values before the code.

Answer 1

[Peter O]

You need to access the title string property of the legend:

There is likely a cleaner method to access this with the new graphics system, but here's how to do it in 2013b:

lh = legend('0','0.5','1');
set(get(lh,'Title'),'String','Gain');