MATLAB: Throw Error in TimerFcn

errorMATLABtimertimerfcn

I want to throw an error when timer fires up . 
try 
   timeout = timer('TimerFcn','error(''TIMEOUT OCCURED'');','StartDelay',0.01);
   start(timeout);
   '''Some Code'''
    stop(timeout);
    delete(timeout);
catch ME
    delete(timeout);
    disp('Error is caught')
    ''' Do something else '''
end
Upon executing, I am getting
Error while evaluating TimerFcn for timer 'timer-47'

Best Answer

This is not going to work as you've written it.
Imagine if the timer's StartDelay was 60 seconds and the body of your try block took 5 seconds to run. Would MATLAB wait, twiddling its thumbs, for 55 seconds for the timer's delay to elapse and then jump into the catch block? No, it wouldn't. By the time the TimerFcn actually executes, the code that created and started the timer may have long since finished.
You could potentially get something like this to work as long as you're willing to have "Some Code" poll. Have the TimerFcn change a value stored somewhere accessible to the function (in the timer object's UserData, for example) and have "Some Code" periodically check if that stored value has changed. If it has, the body of the try has run for too long and "Some Code" should terminate.
Alternately, if you're willing to poll, you don't need a timer. Store the current time (as a datetime would be easist to check) at the start of "Some Code" and periodically check if the difference between the current time and stored time, terminating "Some Code" if it's been too long.
currentTime = datetime('now');
totalPause = 0;
while true
    r = rand;
    disp("About to pause for " + r + " seconds.")
    pause(r)
    totalPause = totalPause + r;
    if datetime('now')-currentTime > seconds(4.5)
        break;
    end
end
end
disp("Paused for a total of " + totalPause + " seconds.")
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