set at every iteration it's just too much data so instead we pick a single point randomly we compute our gradient with respect to that point and then on the next iteration we pick a different point and we can get a rough estimate of our gradient at each step right so instead of using all of our data now we just pick a single point I we compute our gradient with respect to that single point I and what's a middle ground here so the downside of using a single point is that it's going to be very noisy the downside of using all of the points is