MATLAB: How to collect all data strings of an array that meet 2 criteria

loops

I am trying to collect data from an array that meet two criteria. More specifically, I want to start collecting the values of an array that cross a threshold and continue to collect the values in the array until they fall below another threshold. I can do the first part, but I can't figure out how to continue to collect the values until they fall below the second threshold (ThresholdOFF in the below attempt). Can you help me collect continuous values of the array (x) that cross above Threshold and continue to collect until the next value that falls below ThresholdOFF? Then I want the indices of the values that meet these criteria. Here is what I have so far:
 Fs = 8000;                   % samples per second
   dt = 1/Fs;                   % seconds per sample
   StopTime = 0.25;             % seconds

   t = (0:dt:StopTime-dt)';     % seconds
   %%Sine wave:
   Fc = 60;                     % hertz
   x = cos(2*pi*Fc*t);
   % Plot the signal versus time:
   figure;
   plot(t,x);
   xlabel('time (in seconds)');
   title('Signal versus Time');
   zoom xon;
 StDevPower=std(x);
 MeanPower=mean(x);
 Threshold=((StDevPower*1)+MeanPower);
 ThresholdOFF=((StDevPower*0.5)+MeanPower);
 AboveSD=[];
 for j=1:length(x)
     if x(j)>Threshold
         AboveSD=[AboveSD; x(j)];
     end
 end
 figure, plot(AboveSD)

Best Answer

A much more efficient way that does not involve growing the result array through a loop (always going to be slow):
%inputs:
%x: the array, starts below Threshold
%Threshold: start threshold
%ThresholdOff: end threshold
startidx = find(x > Threshold, 1);
endidx = startidx + find(x(startidx+1:end) < ThresholdOff, 1);
AboveSD = x(startidx:endidx-1);
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