#!/usr/bin/env perl 
use strict;
use warnings;
use Benchmark 'cmpthese';

for my $arrsize (1e5, 1e6, 1e7) {
    print "Source array has $arrsize elements\n";
    my @x;
    push @x, rand for 1..$arrsize;

    cmpthese (1e1, {
        BUK => sub { my @y; $y[ $_-1 ] = $x[ $_-1 ] - $x[ $_ ] for 1 .. $#x; },
        ike1 => sub { my @y; $y[ $_ ] = $x[ $_ ] - $x[ $_+1 ] for 0 .. $#x-1; },
        ike2 => sub { my @y = @x; $y[ $_ ] -= $y[ $_+1 ] for 0 .. $#y-1; pop @y; },
        while => sub { my @y; my $i = $#x; $y[ $i ] = $x[ $i ] + $x[ --$i ] while $i; },
    });
    print '-' x 80 . "\n";
}

##</code><code>##

Source array has 100000 elements
            (warning: too few iterations for a reliable count)
            (warning: too few iterations for a reliable count)
            (warning: too few iterations for a reliable count)
            (warning: too few iterations for a reliable count)
        Rate   BUK  ike1 while  ike2
BUK   32.3/s    --  -19%  -32%  -32%
ike1  40.0/s   24%    --  -16%  -16%
while 47.6/s   48%   19%    --   -0%
ike2  47.6/s   48%   19%    0%    --
--------------------------------------------------------------------------------
Source array has 1000000 elements
        Rate   BUK  ike1  ike2 while
BUK   2.79/s    --  -30%  -39%  -42%
ike1  4.00/s   43%    --  -12%  -16%
ike2  4.57/s   63%   14%    --   -5%
while 4.78/s   71%   20%    5%    --
--------------------------------------------------------------------------------
Source array has 10000000 elements
      s/iter   BUK  ike1  ike2 while
BUK     3.06    --  -18%  -28%  -31%
ike1    2.49   23%    --  -11%  -16%
ike2    2.21   38%   13%    --   -5%
while   2.10   46%   19%    5%    --
--------------------------------------------------------------------------------

##</code><code>##

#!/usr/bin/env perl 
use strict;
use warnings;
use Benchmark 'cmpthese';

my @source;

for my $arrsize (1e6, 1e7, 1e8) {
    print "Source array has $arrsize elements\n";
    my @source;
    push @source, rand for 1..$arrsize;

    cmpthese (1e8, {
        'BUK' => ' my @b; $b[ $_-1 ] = $a[ $_-1 ] - $a[ $_ ] for 1 .. $#a; ',
        'ike1' => ' my @b; $b[ $_ ] = $a[ $_ ] - $a[ $_+1 ] for 0 .. $#a-1; ',
        'ike2' => ' my @b = @a; $b[ $_ ] -= $b[ $_+1 ] for 0 .. $#b-1; pop @b; '
    });
    print '-' x 80 . "\n";
}

##</code><code>##

Source array has 1000000 elements
          Rate ike2  BUK ike1
ike2 2347418/s   -- -25% -27%
BUK  3126954/s  33%   --  -3%
ike1 3207184/s  37%   3%   --
--------------------------------------------------------------------------------
Source array has 10000000 elements
          Rate ike2  BUK ike1
ike2 2226180/s   -- -28% -31%
BUK  3079766/s  38%   --  -4%
ike1 3204101/s  44%   4%   --
--------------------------------------------------------------------------------
Source array has 100000000 elements
          Rate ike2 ike1  BUK
ike2 1886792/s   -- -28% -30%
ike1 2612330/s  38%   --  -3%
BUK  2705628/s  43%   4%   --
--------------------------------------------------------------------------------

##</code><code>##

#!/usr/bin/env perl 
use strict;
use warnings;
use Benchmark 'cmpthese';

for my $arrsize (1e4, 1e6, 1e8) {
    print "Source array has $arrsize elements\n";
    my @x;
    push @x, rand for 1..$arrsize;

    cmpthese (1e7, {
        'BUK' => ' my @y; $y[ $_-1 ] = $x[ $_-1 ] - $x[ $_ ] for 1 .. $#x; ',
        'ike1' => ' my @y; $y[ $_ ] = $x[ $_ ] - $x[ $_+1 ] for 0 .. $#x-1; ',
        'ike2' => ' my @y = @x; $y[ $_ ] -= $y[ $_+1 ] for 0 .. $#y-1; pop @y; '
    });
    print '-' x 80 . "\n";
}

##</code><code>##

Source array has 10000 elements
          Rate ike2  BUK ike1
ike2 2309469/s   -- -24% -26%
BUK  3030303/s  31%   --  -3%
ike1 3134796/s  36%   3%   --
--------------------------------------------------------------------------------
Source array has 1000000 elements
          Rate ike2  BUK ike1
ike2 2267574/s   -- -28% -30%
BUK  3164557/s  40%   --  -2%
ike1 3236246/s  43%   2%   --
--------------------------------------------------------------------------------
Source array has 100000000 elements
          Rate ike2  BUK ike1
ike2 2277904/s   -- -23% -28%
BUK  2976190/s  31%   --  -7%
ike1 3184713/s  40%   7%   --
--------------------------------------------------------------------------------