Random Numbers and Bluetooth

I keep losing this page

I came accross this site and having several BT dongles, decided to give it a try.

It relies on the bccmd out of bluez. Worked well with an el cheapo $2 dongle.

The script below produced a low of 0, and a high of 65535, so presumeably it is filling a 16 bit register with 1s and 0s and bccmd is producing a decimal number. My bccmd is a binary, so guess I will have find the source for it somewhere.



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#!/usr/bin/perl

use strict;

my $bccmd = "/usr/sbin/bccmd rand";

my $high_nr = 0;

my $low_nr = 65568;

foreach (1 .. 100000){

my $cmd_output = `$bccmd`;

#print "$cmd_output\n"; # Random number: 0x8fd7 (36823)

if ($cmd_output =~ m/\((\d+)/)

{$high_nr = $1 if ($1 > $high_nr);$low_nr = $1 if ($1 < $low_nr) };

}



print "$low_nr\t$high_nr\n";

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I generated 1000000 random numbers, took 7 hours and 11 minutes (40 numbers per second) and produced a file 5830542 bytes in size.

Then statistics time, but it seems my grasp of stats is extremely poor as I was clueless as to what I was doing. Never the less I took the million decimal numbers and calculated these facts;



Home generated stats:



mean is 32779

Lowest nr is 0

Highest number is 65535



Stats using the perl module Statistics::Descriptive

Minumun Value 0

Lower quantile 16410 (guess expected would be 65536/4 or 16384 - close?)

Second quantile 32786 (expected 65536/2 or 32768 - also close)

Third quantile 49164

Fourth quantile 65535

Number counted 1000000

Mean of count 32779.339758 (expected 32768)



key = 8191.875, count = 124887 (expected is 1000000/8 or 125000)

key = 16383.75, count = 124690

key = 24575.625, count = 125487

key = 32767.5, count = 124680

key = 40959.375, count = 124870

key = 49151.25, count = 125195

key = 57343.125, count = 124590

key = 65535, count = 125601