#!/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";
}