what does this error with tic\toc means?

Question

alex 2012-10-15

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评论： Walter Roberson 2016-1-8

i have this problem - matlab tells me I have an error while running-

 Error using toc
 You must call TIC without an output argument before calling TOC without an
 input argument.
 Error in hand_rotation2/youPress (line 126)
             c = toc;
 Error while evaluating figure KeyPressFcn

what does it mean, and how can I fix it?

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Answer 1

Wayne King 2012-10-15

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编辑：Wayne King 2012-10-15

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It means to use toc, you have to call tic first somewhere

 tic;
 for ii = 1:10
  x(ii) = ii+1;
 end
 y = toc;

If you use toc by itself, it must have been preceded by a tic command sometime during the current session, then it gives the time since the most recent tic command. In this latter case, that is probably not what you want.

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alex 2012-10-15

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well, then I don't understand I I'm getting this error- I have a timer that starts with tic (in the StartFcn) and the user will press the keys only after tic began, and there is the toc..

those are my functions-

function youPress(~,eventdata)
          if eventdata.Key== 'i' 
             c = toc;
             anscell{ii,2}=c;
             anscell{ii,3}='i';
             stop(t)
          elseif eventdata.Key== 'e' 
             c = toc;
             anscell{ii,2}=c;
             anscell{ii,3}='e';
             stop(t)
          end
end
    % code
  end
function timer_started(~,~)
         tic
end
function timer_stop(~,~)
 toc
 set(a7,'Visible','on');
 ii=ii+1;
 if ii<10
 START_TIMER;
 else 
    set(a7,'Visible','off');
    set(a8,'Visible','on');
    set(a9,'Visible','on');
 end
 end
 function START_TIMER(~,~)
        set(a7,'Visible','on');
        pause(plus_time);
        b=unidrnd(size(imcell,2));
        anscell{ii,2}=imcell{2,b};
        set(a7,'Visible','off');
        axes('Position',[.35 .3 .3 .3]);
        image(imcell{1,b});
        start(t);
    end