You decide it. Then just have a while loop where you get the "objective" as you call it. The loop will break once your "objective" is less than your tolerance/threshold:
loopCounter = 1;
maxIterations = 9999999; % Failsafe
objective = inf;
threshold = 10; % Whatever...
while loopCounter < maxIterations && objective > threshold
objective = GetNewObjective(); % However you do it....
loopCounter = loopCounter + 1;
end
