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Re^2: Check randomly generated numbers have not been used before

by BrowserUk (Pope)
on Jun 20, 2014 at 19:28 UTC ( #1090675=note: print w/replies, xml ) Need Help??


in reply to Re: Check randomly generated numbers have not been used before
in thread Check randomly generated numbers have not been used before

If you had any programming skills, you'd make some attempt to verify a wild-assed guess like that:

#! perl -slw use strict; use Math::Random::MT qw[ rand ]; our $T //= 50; my( $total, $min, $max ) = ( 0, 1e9, 0 ); for( 1 .. $T ) { my( %h, $r ); while( 1 ) { $r = int( 1e6 + rand( 9e6 ) ); ++$h{ $r } == 2 and last; } my $subt = scalar keys %h; $total += $subt; $min = $subt if $subt < $min; $max = $subt if $subt > $max; printf "Duplicate value($r) seen after %d iterations\n", $subt; } printf "Ave.%.3f Min:%d Max:%d\n", $total / $T, $min, $max; __END__ C:\test>junk54 Duplicate value(2665199) seen after 4496 iterations Duplicate value(6555509) seen after 5166 iterations Duplicate value(8242500) seen after 1302 iterations Duplicate value(8032591) seen after 1597 iterations Duplicate value(6169187) seen after 4540 iterations Duplicate value(3999236) seen after 6578 iterations Duplicate value(4470150) seen after 7858 iterations Duplicate value(4580644) seen after 3798 iterations Duplicate value(4856238) seen after 4780 iterations Duplicate value(9540961) seen after 1793 iterations Duplicate value(8106058) seen after 5114 iterations Duplicate value(8231462) seen after 1289 iterations Duplicate value(5437248) seen after 1915 iterations Duplicate value(6177470) seen after 2986 iterations Duplicate value(7463793) seen after 3506 iterations Duplicate value(3028064) seen after 5916 iterations Duplicate value(9985723) seen after 1536 iterations Duplicate value(4848638) seen after 1384 iterations Duplicate value(1227666) seen after 3463 iterations Duplicate value(8764243) seen after 4122 iterations Duplicate value(6364225) seen after 5994 iterations Duplicate value(5322923) seen after 506 iterations Duplicate value(7557328) seen after 1820 iterations Duplicate value(4731867) seen after 2791 iterations Duplicate value(8199944) seen after 1903 iterations Duplicate value(8481265) seen after 4763 iterations Duplicate value(5209684) seen after 1039 iterations Duplicate value(3202941) seen after 6198 iterations Duplicate value(6657755) seen after 5574 iterations Duplicate value(7013349) seen after 2369 iterations Duplicate value(7736365) seen after 3088 iterations Duplicate value(3171737) seen after 1359 iterations Duplicate value(5533710) seen after 2921 iterations Duplicate value(9403663) seen after 2459 iterations Duplicate value(8811253) seen after 4271 iterations Duplicate value(1649095) seen after 5702 iterations Duplicate value(4630011) seen after 3550 iterations Duplicate value(9044573) seen after 6169 iterations Duplicate value(5711853) seen after 4171 iterations Duplicate value(3313811) seen after 2539 iterations Duplicate value(5055725) seen after 5712 iterations Duplicate value(6910134) seen after 4571 iterations Duplicate value(5598759) seen after 6135 iterations Duplicate value(8065116) seen after 2466 iterations Duplicate value(4587634) seen after 6195 iterations Duplicate value(4192726) seen after 1373 iterations Duplicate value(4299363) seen after 5448 iterations Duplicate value(2418217) seen after 4396 iterations Duplicate value(2225622) seen after 1414 iterations Duplicate value(4347823) seen after 1962 iterations Ave.3639.940 Min:506 Max:7858

Using one of the best PRNGs around, that hits a duplicate after less than 4000 attempts on average, and as few 500.

Best you stick to your fluff pieces, handing out bad advice that could ruin young guys careers; at least then you cannot be proven wrong!.


With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

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