shouldPlot and switch case and legend and multiple figure error

Two questions about shouldPlot and switchcase:

1) I cannot locate correctly legends I mean it does not show legends for figure (1) 2) Figure (2) cannot be shown. I can usse another swicthcase but I do not want to overwrite.

   shouldPlot = true;
      switch nt
          case 1
              f = up;     g = down; 
              c = middle;
              vel1 = u1;  vel2 = u2;
              hold on;
          case 2
              f = up;     g = down;  
              c = middle;
              vel1 = u1;  vel2 = u2;
          otherwise
              shouldPlot = false;
              %               disp('Quit');
      end
      if (shouldPlot)
          figure (1);
          plot(xx,f,xx,g);
          legend('time 0','time 0','t clash','t clash')
          hold on;
          plot(xx, c);
  %         legend('time 0','t clash')
          hold on
  %         axis([0 1 0 1]);
          xlabel('x');
          ylabel('body');

          figure (2);
          plot(xx,vel1,xx,vel2);
          ...
        end

Answer 1

[Michael Haderlein]

When I run the code inside your if case with random values, I do get the legend in figure 1. Of course, only f and g are described, but that's all which is plotted at the time the legend is created. Depending on the size of f and g, the legend either includes only "time 0" twice or also "t clash". c is not included in the legend as you plot c after the creation of the legend. Remember that the legend will be fully rewritten when you use the legend command. Old entries will disappear if you do not repeat them.

What do you mean with "Figure (2) cannot be shown."? Figure 2 is created and shows up just as it should.

[Meva]

I see. But I have tried to use legend just after plot of constriction and it again did not work.

Figure (2) does not show up. I thought maybe I have locate somewhere it should not be.

[Michael Haderlein]

What happens if you run

figure
plot(rand(2),rand(2))
legend('A','B')

With respect to your original problem: Do you get an error or is just nothing showing up?

[Meva]

legend certainly does not work.. I have used :

   shouldPlot = true;
        switch nt
            case 1
            ...
            case 2
            ...
            otherwise
                shouldPlot = false;
                ...
        end

         if (shouldPlot)
            figure (1);
            plot(xx,f,xx,g);
            hold on;
            plot(xx, c);
            legend('for f case1','for g case1','or f case2', 
            'for g case2','for c case 1','for c case2')
            hold on
            xlabel('...');
            ylabel('...');
            figure (2);
            plot(xx,vel1,xx,vel2);
            ...
          end

How can I show the lines names without legend is there another way?

[Meva]

Hi Michael, nothing show up does not give me an error.