%perlcode %{
@EXPORT_OK = qw/
gsl_combination_alloc
gsl_combination_calloc
gsl_combination_init_first
gsl_combination_init_last
gsl_combination_free
gsl_combination_memcpy
gsl_combination_fread
gsl_combination_fwrite
gsl_combination_fscanf
gsl_combination_fprintf
gsl_combination_n
gsl_combination_k
gsl_combination_data
gsl_combination_get
gsl_combination_valid
gsl_combination_next
gsl_combination_prev
/;
%EXPORT_TAGS = ( all => [ @EXPORT_OK ] );
=encoding utf8
=head1 NAME
Math::GSL::Combination - Combinations
=head1 SYNOPSIS
use Math::GSL qw/:all/;
use Math::GSL::Combination qw/:all/;
my $c = Math::GSL::Combination->new(6,3);
print join (" ", $c->as_list) . "\n";
$c->next;
print join (" ", $c->as_list) . "\n";
my $fd = gsl_fopen('combination.dat', 'w');
gsl_combination_fwrite($fd, $c->raw);
gsl_fclose($fd);
=head1 DESCRIPTION
Here is a list of all the functions in this module :
=over
=item * C<gsl_combination_alloc($n, $k)>
This function allocates memory for a new combination with parameters $n, $k.
The combination is not initialized and its elements are undefined. Use the
function gsl_combination_calloc if you want to create a combination which is
initialized to the lexicographically first combination.
=item * C<gsl_combination_calloc($n, $k)>
This function allocates memory for a new combination with parameters $n, $k and
initializes it to the lexicographically first combination.
=item * C<gsl_combination_init_first($c)>
This function initializes the combination $c to the lexicographically first
combination, i.e. (0,1,2,...,k-1).
=item * C<gsl_combination_init_last($c)>
This function initializes the combination $c to the lexicographically last
combination, i.e. (n-k,n-k+1,...,n-1).
=item * C<gsl_combination_free($c)>
This function frees all the memory used by the combination $c.
=item * C<gsl_combination_memcpy($dest, $src)>
This function copies the elements of the combination $src into the combination
$dest. The two combinations must have the same size.
=item * C<gsl_combination_get($c, $i)>
This function returns the value of the i-th element of the combination $c. If
$i lies outside the allowed range of 0 to k-1 then the error handler is invoked
and 0 is returned.
=item * C<gsl_combination_fwrite($stream, $c)>
This function writes the elements of the combination $c to the stream $stream,
opened with the gsl_fopen function from the Math::GSL module, in binary format.
The function returns $GSL_EFAILED if there was a problem writing to the file.
Since the data is written in the native binary format it may not be portable
between different architectures.
=item * C<gsl_combination_fread($stream, $c)>
This function reads elements from the open stream $stream, opened with the
gsl_fopen function from the Math::GSL module, into the combination $c in binary
format. The combination $c must be preallocated with correct values of n and k
since the function uses the size of $c to determine how many bytes to read. The
function returns $GSL_EFAILED if there was a problem reading from the file. The
data is assumed to have been written in the native binary format on the same
architecture.
=item * C<gsl_combination_fprintf($stream, $c, $format)>
This function writes the elements of the combination $c line-by-line to the
stream $stream, opened with the gsl_fopen function from the Math::GSL module,
using the format specifier $format, which should be suitable for a type of
size_t. In ISO C99 the type modifier z represents size_t, so "%zu\n" is a
suitable format. The function returns $GSL_EFAILED if there was a problem
writing to the file.
=item * C<gsl_combination_fscanf($stream, $c)>
This function reads formatted data from the stream $stream into the combination
$c. The combination $c must be preallocated with correct values of n and k
since the function uses the size of $c to determine how many numbers to read.
The function returns $GSL_EFAILED if there was a problem reading from the file.
=item * C<gsl_combination_n($c)>
This function returns the range (n) of the combination $c.
=item * C<gsl_combination_k($c)>
This function returns the number of elements (k) in the combination $c.
=item * C<gsl_combination_data($c)>
This function returns a pointer to the array of elements in the combination $c.
=item * C<gsl_combination_valid($c)>
This function checks that the combination $c is valid. The k elements should
lie in the range 0 to n-1, with each value occurring once at most and in
increasing order.
=item * C<gsl_combination_next($c)>
This function advances the combination $c to the next combination in
lexicographic order and returns $GSL_SUCCESS. If no further combinations are
available it returns $GSL_FAILURE and leaves $c unmodified. Starting with the
first combination and repeatedly applying this function will iterate through
all possible combinations of a given order.
=item * C<gsl_combination_prev($c)>
This function steps backwards from the combination $c to the previous
combination in lexicographic order, returning $GSL_SUCCESS. If no previous
combination is available it returns $GSL_FAILURE and leaves $c unmodified.
=back
=cut
sub new {
my ($class, $n, $k) = @_;
my $this = {};
$this->{_length} = $n;
$this->{_combination} = gsl_combination_calloc($n, $k);
bless $this, $class;
}
sub as_list {
my $self=shift;
$self->get( [ 0 .. $self->elements - 1 ] );
}
sub get {
my ($self, $indices) = @_;
return map { gsl_combination_get($self->{_combination}, $_ ) } @$indices ;
}
sub raw { (shift)->{_combination} }
sub length { (shift)->{_length} }
sub elements {
my $self = shift;
return gsl_combination_k($self->{_combination});
}
sub status {
my ($self,$status) = @_;
if (defined $status) {
$self->{status} = $status;
return $self;
} else {
return $self->{status};
}
}
sub next {
my $self = shift;
my $status = gsl_combination_next($self->{_combination});
$self->status($status);
return $self;
}
sub prev {
my $self = shift;
my $status = gsl_combination_prev($self->{_combination});
$self->status($status);
return $status;
}
=head1 MORE INFO
For more informations on the functions, we refer you to the GSL offcial
documentation: L<http://www.gnu.org/software/gsl/manual/html_node/>
=head1 AUTHORS
Jonathan "Duke" Leto <jonathan@leto.net> and Thierry Moisan <thierry.moisan@gmail.com>
=head1 COPYRIGHT AND LICENSE
Copyright (C) 2008-2011 Jonathan "Duke" Leto and Thierry Moisan
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
=cut
%}