https://wiki.kram.nz/index.php?action=history&feed=atom&title=SE250%3Alab-5%3Akkan048 2026-04-28T23:52:35Z Revision history for this page on the wiki MediaWiki 1.45.3 https://wiki.kram.nz/index.php?title=SE250:lab-5:kkan048&diff=6586&oldid=prev 2008-11-03T05:19:48Z

<p>21 revision(s)</p> <p><b>New page</b></p><div>This is my testing condition.<br /> int sample_size = 300;<br /> int n_keys = 1000;<br /> int table_size = 100;<br /> <br /> Sample_size can not be too low/high.If it is too low/high,the results between different function will not be shown.<br /> <br /> buzhash is a most common hash function.So i think it is a high standard function in the test.<br /> buzhash has a Entropy greater than 7 just after sample_size 300.<br /> So i choose 300 as a sample size.<br /> <br /> &lt;pre&gt;<br /> SAMPLE SIZE 300<br /> <br /> In Typical entropy source,<br /> buzhash buzhashn hash CRC base256 <br /> Entropy : 7.258579 7.392708 6.288118 3.901501<br /> Optimum compression: 9% 7% 21% 51%<br /> Chi square: 25.00% 99.00% 0.01% 0.01%<br /> Arithmetic mean:(127.5 = random) 127.6200 122.2267 101.9633 103<br /> Monte Carlo error: 6.95% 4.41% 4.41% 27.32%<br /> Serial correlation coefficient: 0.030493 0.035384 0.072278 0.282614<br /> (totally uncorrelated = 0.0)<br /> <br /> <br /> In Low entropy source,<br /> <br /> buzhash buzhashn hash CRC base256 <br /> Entropy : 7.348095 7.392708 3.614340 0.000000<br /> Optimum compression: 8% 7% 54% 100%<br /> Chi square: 75.00% 99.00% 0.01% 0.01%<br /> Arithmetic mean:(127.5 = random) 131.6200 122.2267 94.1633 97<br /> Monte Carlo error: 3.23% 4.41% 27.32% 27.32%<br /> Serial correlation coefficient: -0.083985 0.035384 -0.386868 all values equal!<br /> (totally uncorrelated = 0.0)<br /> &lt;/pre&gt;<br /> <br /> <br /> &lt;pre&gt;<br /> <br /> Unix Random Number Generator<br /> <br /> SAMPLE SIZE 300<br /> <br /> In Typical entropy source,<br /> Rand high_rand <br /> Entropy of the output : 7.258579 7.392708 <br /> Optimum compression: 9% 7% <br /> Chi square: 25.00% 99.00% <br /> Arithmetic mean:(127.5 = random) 127.6200 122.2267 <br /> Monte Carlo error: 6.95% 4.41% <br /> Serial correlation coefficient: 0.030493 0.035384 <br /> (totally uncorrelated = 0.0)<br /> <br /> <br /> In Low entropy source,<br /> <br /> Rand high_rand<br /> Entropy of the output : 7.317278 7.247632 <br /> Optimum compression: 8% 9% <br /> Chi square: 50.00% 25.00% <br /> Arithmetic mean:(127.5 = random) 108.3600 128.2033 <br /> Monte Carlo error: 14.59% 0.69% <br /> Serial correlation coefficient: -0.041849 0.010037 <br /> (totally uncorrelated = 0.0)<br /> &lt;/pre&gt;<br /> <br /> I am still looking at the randomness meaning of the individual output parameters.<br /> So i just rank them in 3 group.<br /> &lt;pre&gt;<br /> Rank 1:buzhash,buzhashn,UNRG<br /> Rank 2:hash CRC<br /> Rank 3:base256<br /> &lt;/pre&gt;</div>

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