f(x) = (a*x + b) % m #### sub gcd { $_[1] ? gcd($_[1], $_[0] % $_[1]) : $_[0] } sub shuffle { my ($seed, $max, $i) = @_; my $ca = $seed; $ca-- until gcd($ca, $max) == 1; my $cb = $seed - $ca; ($ca * $i + $cb) % $max; } for my $seed (1 .. 10) { my @result = map shuffle($seed, 15, $_), 0 .. 14; print "seed=$seed ==> @result\n"; } #### seed=1 ==> 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 seed=2 ==> 0 2 4 6 8 10 12 14 1 3 5 7 9 11 13 seed=3 ==> 1 3 5 7 9 11 13 0 2 4 6 8 10 12 14 seed=4 ==> 0 4 8 12 1 5 9 13 2 6 10 14 3 7 11 seed=5 ==> 1 5 9 13 2 6 10 14 3 7 11 0 4 8 12 seed=6 ==> 2 6 10 14 3 7 11 0 4 8 12 1 5 9 13 seed=7 ==> 0 7 14 6 13 5 12 4 11 3 10 2 9 1 8 seed=8 ==> 0 8 1 9 2 10 3 11 4 12 5 13 6 14 7 seed=9 ==> 1 9 2 10 3 11 4 12 5 13 6 14 7 0 8 seed=10 ==> 2 10 3 11 4 12 5 13 6 14 7 0 8 1 9