ESTIMATING MANIPULATION ERRORS IN FINITE ELEMENT ANALYSIS, PART II.

Part I of this paper described the errors in processing numbers with digital computers. Part II presents and illustrates the effectiveness of error estimation for three goals: pre-estimating, measuring actual errors, and identifying the error source. Pre-estimation is intended to eliminate analyses whose results would be inaccurate. Measurement of actual errors qualifies the accuracy of calculations. Error source identification leads to selection of error reduction methods. The authors conclude that bound estimates of lost precision are excessively high, do not correlate with actual round-off errors, and are not reliable in identifying the key sources of error. Experiments show that the closure measure provides excellent estimates of maximum error in stress predictions. This fact suggests a conservative approach to protect against use of inaccurate analysis results.