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lib/AI/SimulatedAnnealing.pm  view on Meta::CPAN

# number representing a cost to be minimized).  The method tests every
# possible combination of numbers matching the specifications and returns a
# reference to an array containing the optimal numbers, where "optimal"
# means producing the lowest cost.
sub use_brute_force {
    my $number_specs = validate_number_specs($_[0]);
    my $cost_function = $_[1];

    my @optimized_list;
    my @lists;
    my @cursors;

    # Populate the list of lists of numbers:
    for my $number_spec (@{ $number_specs }) {
        my @list;
        my $num = $number_spec->{"LowerBound"};

        while ($num <= $number_spec->{"UpperBound"}) {
            push @list, $num;
            $num += 1 / (10 ** $number_spec->{"Precision"});
        } # end while

        push @lists, \@list;
    } # next $number_spec

    # Populate @cursors with the starting position for each list of numbers:
    for (0..$#lists) {
        push @cursors, 0;
    } # next

    # Perform the tests:
    my $lowest_cost = undef;
    my $finished = $FALSE;

    do {
        # Perform a test using the current cursors:
        my @candidate_list;
        my $cost;

        for my $dex (0..$#lists) {
            push @candidate_list, $lists[$dex]->[$cursors[$dex]];
        } # next $dex

        $cost = $cost_function->(\@candidate_list);

        unless (defined($lowest_cost) && $cost >= $lowest_cost) {
            $lowest_cost = $cost;
            @optimized_list = @candidate_list;
        } # end unless

        # Adjust the cursors for the next test if not finished:
        for my $dex (reverse(0..$#lists)) {
            my $cursor = $cursors[$dex];

            if ($cursor < $#{ $lists[$dex] }) {
                $cursor++;
                $cursors[$dex] = $cursor;
                last;
            }
            elsif ($dex == 0) {
                $finished = $TRUE;
                last;
            }
            else {
                $cursors[$dex] = 0;
            } # end if
        } # next $dex
    } until ($finished);

    # Return the result:
    return \@optimized_list;
} # end sub

# The validate_number_specs() function takes a reference to an array of
# number specifications (which are references to hashes with "LowerBound",