Trouble using switch case

 Below is example code. I am running into problems when theState becomes 'ACTIVE.' I am looking to see it stay in that 'ACTIVE' state until criteria is met. Thus it should fprintf('Still Active'),... well in my world at least :).

 What am I missing here, is it problematic to use switch/case inside of switch/case. Or is there a massive user error!

    % theState = 'INACTIVE'; this is where we start. In 'INACTIVE' 
     x = 1; y = -0.5;
   for i = 1:100
  switch theState
      case 'INACTIVE'
          if x == 1
              %yadaYada
              theState = 'ACTIVE';
              whereActive = 'kramer';
              fprintf('ACTIVE kramer \n');
          elseif x == 2
              %yadaYada

              theState = 'ACTIVE';
              whereActive = 'george';
              fprintf('ACTIVE george \n');
          end
      case 'ACTIVE'
          switch whereActive
              case 'kramer'
                  if y >= 1
                      %yadaYada
                      theState = 'INACTIVE';
                      fprintf('INACTIVE by kramer');
                  end
              case 'george'
                  if y <= -1
                      %yadaYada
                      theState = 'INACTIVE';
                      fprintf('INACTIVE by george');
                  end
              otherwise
                  fprintf('Still Active');
          end
  end
  end

Answer 1

[Jan]

This is a job for the line-by-line debugging. Set a breakpoint in each line, which changes or tests the internal states. Then run the program agian and observe how your system is developping.

Computers are not smart. But in running a program step by step they are really and absolutely perfect. Therefore it is much more efficient, when you do this locally instead of letting members of the forum doing this remotely without having the full code.

[Scotty]

Jan,

Thanks you always have good feedback.

I actually did that (i rarely ask question here) but only with breakpoints at specific areas. I will look to put in several... however the logic of the code is there.

consider when in an active state stay in that state until criteria is met. Then return to inactive... is what i am trying to get at.

[Scotty]

Got it thanks Jan!

I stepped through it with about 30 breakpoints..took a bit but it worked.

Answer 2

[Matt J]

A few observations

1. You never change whereActive to anything other than kramer or george, so the "otherwise" block where fprintf('Still Active') lies never gets executed.
2. You never change y to satisfy y<=-1 or y>=1, so the cases 'kramer' and 'george' under 'ACTIVE' never do any work

[Scotty]

Matt

thanks for the fast reply. Still shaking my head at this.

ok hmmm "1. You never change whereActive ... lies never gets executed."

Ok then why should it NOT tell me the 'theState' is still 'ACTIVE' even though the criteria for y has not been met?

I know that y has not been met as far as the 2nd observation as it was intended. But when you change y to y = -1.5 you will still not see it exit the 'ACTIVE' state and cast theState = 'INACTIVE' to begin again.

What am i missing?

[Matt J]

Ok then why should it NOT tell me the 'theState' is still 'ACTIVE' even though the criteria for y has not been met?

Because you have criteria for both y and whereActive, which need to be simultaneously satisfied in order for something to happen. They never are, however.

But when you change y to y = -1.5 you will still not see it exit the 'ACTIVE'

As a case in point, y=-1.5 will only trigger something if whereActive='george'. That never happens.

[Scotty]

Oh god... my dyslexia is kicking in... I solved my problem it works as intended.

thanks.

Answer 3

[Thorsten]

I think you can fix it if you put the "if y " first in the 'ACTIVE' case and then switch depending on whereActive

case 'ACTIVE'
  if abs(y) < 1
    fprint('Still active')
  else

      switch whereActive
        case 'kramer'
          if y >= 1
            %yadaYada
            theState = 'INACTIVE';
            fprintf('INACTIVE by kramer');
          end
        case 'george'
          if y <= -1
            %yadaYada
             theState = 'INACTIVE';
             fprintf('INACTIVE by george');
           end
       end

    end % if abs(y) < 0.5