The iteration process continues until {HEAD ~ the predicted values} match the measured values within {TAIL ~ a desired degree} of tolerance 
The iteration process continues until { HEAD ~ the predicted values } match the measured values within { TAIL ~ a desired degree } of tolerance
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH