Hello All, Rather than replying to previous messages I felt it would be better to start a new and more appropriately titled thread. In the ongoing quest to try and develop a timing system for in-code use and (now) benchmarking as an example application the original code of Joel de Guzman has been extensively modified and uploaded here: http://tinyurl.com/nmhthy The code uses two techniques for calculating the percentage speedup. It is quite likely that the error estimate for the actual run times is very wrong. I strongly suspect that the random error is over- estimated but the systematic error is under-estimated. Note that changing the machine loading can affect the absolute times noticeably. Burst-like behaviour will not matter too much, but sustained loading will. Consequently if you wish to directly compare the ns/char (nanoseconds per character) values between runs or machines care should be taken to make sure the background load is consistent. When looking at the relative times on a given run - particularly with the Wilcoxon test, this is far less important. I look forward to results anyone gets on other machines. Particularly with respect to robustness of the results against background processes, repeatability and or inter-compiler variations. Cheers, -ed $ echo 1000 15 | ./ejg_uint Enter buffer size: Enter nominal precision (%): initializing input strings... Nominal precision of quantum: 15% Timer overhead (t_c) (ticks): 108.321 Jitter (ticks): 8.24459 Approx clock frequency (GHz): 2.1681 Direct point estimates of actual run time. Function T - delta T (best) T + delta (ns/char) (ns/char) (ns/char) qi_parse 47 67 87 strtol 74 1.1e+02 1.4e+02 atoi 79 1.1e+02 1.5e+02 Speedup percentages based on Wilcoxon matched pair confidence intervals. Func. A vs Func. B Minimum Median Maximum (% faster) (% faster) (% faster) qi_parse atoi 69 69.2 69.3 qi_parse strtol 57.8 57.9 58 strtol atoi 7.14 7.16 7.2 qi_parse qi_parse -0.0762 0.00468 0.0343 Speedup percentages based on the point estimates. Func. A vs Func. B Best - err Best Best + err (% faster) (% faster) (% faster) qi_parse atoi 63.1 69.1 75.1 qi_parse strtol 51.8 57.8 63.8 strtol atoi 1.16 7.16 13.2 qi_parse qi_parse -6 0.00222 6 All done! ------------------------------------------------ "No more boom and bust." -- Dr. J. G. Brown, 1997