#! perl -slw
use strict;

my @data;
$data[ $_ ] = [ map int( rand 100 ), 1 .. 10 ] for 0 .. 1e3;

my @lookback;
my $matches = 0;
for my $row ( @data ) {
    for my $lb ( @lookback ) {
        if( $row->[ 3 ] < 10  && $lb->[ 7 ] > 50 ) {
            print "condition matched ", ++$matches;
            last;
        }
    }

    push @lookback, $row;
    shift @lookback if @lookback > 15;
}