
# This file is automatically created by Core.pm.PL
# Do not edit this file -- all changes will be lost

# - bad value support = 0


=head1 NAME

PDL::Core - fundamental PDL functionality

=head1 DESCRIPTION

Methods and functions for type conversions, PDL creation,
type conversion, threading etc.

=head1 SYNOPSIS

 use PDL::Core;             # Normal routines
 use PDL::Core ':Internal'; # Hairy routines

=head1 FUNCTIONS

=cut

# Core routines for PDL module

package PDL::Core;
use PDL::Types;

$PDL::Core::FOO_FOO_::VERSION = '1.56';

# Functions exportable in this part of the module

@EXPORT = qw( piddle pdl null barf ); # Only stuff always exported!


@EXPORT_OK = qw( howbig threadids topdl nelem dims null
   byte short ushort long longlong float double
   convert inplace zeroes ones list listindices
   set at flows thread_define over reshape dog cat barf type diagonal
   dummy mslice approx flat sclr squeeze
   );

%EXPORT_TAGS = (
   Func=>[qw/nelem dims null
    byte short ushort long longlong float double
    convert inplace zeroes ones list listindices
    set at flows thread_define over reshape pdl piddle null dog cat barf type
    diagonal dummy mslice approx flat sclr
    /],
   Internal=>[qw/howbig threadids topdl/]
);


use PDL::Exporter;
use DynaLoader;

@ISA    = qw( PDL::Exporter DynaLoader );

use strict;
use vars qw($level @dims $sep $sep2 $match);
bootstrap PDL::Core;

# Important variables (place in PDL namespace)
# (twice to eat "used only once" warning)

$PDL::debug      =	     # Debugging info
$PDL::debug      = 0;
$PDL::verbose      =	     # Functions provide chatty information
$PDL::verbose      = 0;
$PDL::use_commas   = 0;        # Whether to insert commas when printing arrays
$PDL::floatformat  = "%7g";    # Default print format for long numbers
$PDL::doubleformat = "%10.8g";
$PDL::undefval     = 0;        # Value to use instead of undef when creating
                               # PDLs

################ Exportable functions of the Core ######################

# log10() is now defined in ops.pd

*howbig       = \&PDL::howbig;	  
*nelem        = \&PDL::nelem;	  *inplace	= \&PDL::inplace;
*dims	      = \&PDL::dims;	  *list 	= \&PDL::list;
*threadids    = \&PDL::threadids; *listindices  = \&PDL::listindices;
*null	      = \&PDL::null;	  *set  	= \&PDL::set;
*at		= \&PDL::at;	  *flows	= \&PDL::flows;
*sclr           = \&PDL::sclr;
*byte = \&PDL::byte;
*short = \&PDL::short;
*ushort = \&PDL::ushort;
*long = \&PDL::long;
*longlong = \&PDL::longlong;
*float = \&PDL::float;
*double = \&PDL::double;

*thread_define = \&PDL::thread_define;
*convert      = \&PDL::convert;   *over 	 = \&PDL::over;
*dog          = \&PDL::dog;       *cat 	         = \&PDL::cat;
*type         = \&PDL::type;      *approx        = \&PDL::approx;
*diagonal     = \&PDL::diagonal;
*dummy        = \&PDL::dummy;
*mslice       = \&PDL::mslice;
*isempty      = \&PDL::isempty;
*string       = \&PDL::string;
sub barf;

##################################################################
##################################################################

=head2 pdl

=for ref

piddle constructor - creates new piddle from perl scalars/arrays and piddles

=for usage

 $a = pdl(SCALAR|ARRAY REFERENCE|ARRAY);

=for example

 $a = pdl [1..10];             # 1D array
 $a = pdl ([1..10]);           # 1D array
 $a = pdl (1,2,3,4);           # Ditto
 $b = pdl [[1,2,3],[4,5,6]];   # 2D 3x2 array
 $b = pdl 42                   # 0-dimensional scalar
 $c = pdl $a;                  # Make a new copy
 $a = pdl([1,2,3],[4,5,6]);    # 2D
 $a = pdl([[1,2,3],[4,5,6]]);  # 2D

Note the last two are equivalent - a list is automatically
converted to a list reference for syntactic convenience. i.e. you
can omit the outer C<[]>

You can mix and match arrays, array refs, and PDLs in your argument
list, and C<pdl> will sort them out.  You get back a PDL whose last
(slowest running) dim runs across the top level of the list you hand
in, and whose first (fastest running) dim runs across the deepest
level that you supply.

Throwing a PDL into the mix has the same effect as throwing in a list ref:

  pdl(pdl(1,2),[3,4])

is the same as 
  
  pdl([1,2],[3,4]).

All of the dimensions in the list are "padded-out" with undefval to
meet the widest dim in the list, so (e.g.)

  $a = pdl([[1,2,3],[2]])

gives you the same answer as 
  
  $a = pdl([[1,2,3],[2,undef,undef]]);



C<pdl()> is a functional synonym for the 'new' constructor,
e.g.:

 $x = new PDL [1..10];

In order to control how undefs are handled in converting from perl lists to
PDLs, one can set the variable C<$PDL::undefval>.
For example:

 $foo = [[1,2,undef],[undef,3,4]];
 $PDL::undefval = -999;
 $f = pdl $foo;
 print $f
 [
  [   1    2 -999]
  [-999    3    4]
 ]

C<$PDL::undefval> defaults to zero.

=cut

sub pdl {PDL->pdl(@_)}

sub piddle {PDL->pdl(@_)}

=head2 null

=for ref

Returns a 'null' piddle.

=for usage

 $x = null;

C<null()> has a special meaning to L<PDL::PP|PDL::PP>. It is used to
flag a special kind of empty piddle, which can grow to
appropriate dimensions to store a result (as opposed to
storing a result in an existing piddle).

=for example

 perldl> sumover sequence(10,10), $ans=null;p $ans
 [45 145 245 345 445 545 645 745 845 945]

=cut

sub PDL::null{
	my $class = scalar(@_) ? shift : undef; # if this sub called with no
						#  class ( i.e. like 'null()', instead
						#  of '$obj->null' or 'CLASS->null', setup
						
	if( defined($class) ){
		$class = ref($class) || $class;  # get the class name
	}
	else{
		$class = 'PDL';  # set class to the current package name if null called
					# with no arguments
	}

	return $class->initialize();
}

=head2 nullcreate

=for ref

Returns a 'null' piddle.

=for usage

 $x = PDL->nullcreate($arg)

This is an routine used by many of the threading primitives
(i.e. L<sumover|PDL::Primitive/sumover>, 
L<minimum|PDL::Primitive/minimum>, etc.) to generate a null piddle for the
function's output that will behave properly for derived (or
subclassed) PDL objects.

For the above usage:
If C<$arg> is a PDL, or a derived PDL, then C<$arg-E<gt>null> is returned. 
If C<$arg> is a scalar (i.e. a zero-dimensional PDL) then C<$PDL-E<gt>null> 
is returned.

=for example

 PDL::Derived->nullcreate(10)
   returns PDL::Derived->null.
 PDL->nullcreate($pdlderived)
   returns $pdlderived->null.

=cut

sub PDL::nullcreate{
	my ($type,$arg) = @_;
        return ref($arg) ? $arg->null : $type->null ;
}

=head2 nelem

=for ref

Return the number of elements in a piddle

=for usage

 $n = nelem($piddle); $n = $piddle->nelem;

=for example

 $mean = sum($data)/nelem($data);

=head2 dims

=for ref

Return piddle dimensions as a perl list

=for usage

 @dims = $piddle->dims;  @dims = dims($piddle);

=for example

 perldl> p @tmp = dims zeroes 10,3,22
 10 3 22

=head2 ndims

=for ref

Returns the number of dimensions in a piddle. Alias
for L<getndims|PDL::Core/getndims>.

=head2 getndims

=for ref

Returns the number of dimensions in a piddle

=for usage

 $ndims = $piddle->getndims;

=for example

 perldl> p zeroes(10,3,22)->getndims
 3

=head2 dim

=for ref

Returns the size of the given dimension of a piddle. Alias
for L<getdim|PDL::Core/getdim>.

=head2 getdim

=for ref

Returns the size of the given dimension.

=for usage

 $dim0 = $piddle->getdim(0);

=for example

 perldl> p zeroes(10,3,22)->getdim(1)
 3

Negative indices count from the end of the dims array.
Indices beyond the end will return a size of 1. This
reflects the idea that any pdl is equivalent to an
infinitely dimensional array in which only a finite number of
dimensions have a size different from one. For example, in that sense a
3D piddle of shape [3,5,2] is equivalent to a [3,5,2,1,1,1,1,1,....]
piddle. Accordingly,

  print $a->getdim(10000);

will print 1 for most practically encountered piddles.

=head2 topdl

=for ref

alternate piddle constructor - ensures arg is a piddle

=for usage

 $a = topdl(SCALAR|ARRAY REFERENCE|ARRAY);

The difference between L<pdl()|/pdl> and C<topdl()> is that the
latter will just 'fall through' if the argument is
already a piddle. It will return a reference and I<NOT>
a new copy.

This is particulary useful if you are writing a function
which is doing some fiddling with internals and assumes
a piddle argument (e.g. for method calls). Using C<topdl()>
will ensure nothing breaks if passed with '2'.

Note that C<topdl()> is not exported by default (see example
below for usage). 

=for example

 use PDL::Core ':Internal'; # use the internal routines of 
                            # the Core module

 $a = topdl 43;             # $a is piddle with value '43'
 $b = topdl $piddle;        # fall through
 $a = topdl (1,2,3,4);      # Convert 1D array

=head2 PDL::get_datatype

=for ref

Internal: Return the numeric value identifying the piddle datatype

=for usage

 $x = $piddle->get_datatype;

Mainly used for internal routines.

NOTE: get_datatype returns 'just a number' not any special
type object, unlike L<type|/type>.

=head2 howbig

=for ref

Returns the size of a piddle datatype in bytes.

Note that C<howbig()> is not exported by default (see example
below for usage). 

=for usage

 use PDL::Core ':Internal'; # use the internal routines of 
                            # the Core module

 $size = howbig($piddle->get_datatype);

Mainly used for internal routines.

NOTE: NOT a method! This is because get_datatype returns
'just a number' not any special object.

=for example

 perldl> p howbig(ushort([1..10])->get_datatype)
 2


=head2 get_dataref

=for ref

Return the internal data for a piddle, as a perl SCALAR ref.  

Most piddles hold their internal data in a packed perl string, to take
advantage of perl's memory management.  This gives you direct access
to the string, which is handy when you need to manipulate the binary
data directly (e.g. for file I/O).  If you modify the string, you'll
need to call L<upd_data|upd_data> afterward, to make sure that the
piddle points to the new location of the underlying perl variable.

You shouldn't mess with the SV unless you've called
L<make_physical|/make_physical> or something similar.  You definitely
don't want to do anything to the SV to truncate or deallocate the
string, unless you correspondingly call L<reshape|/reshape> to make the
PDL match its new data dimension.

You definitely don't want to use get_dataref unless you know what you
are doing (or are trying to find out): you can end up scrozzling
memory if you shrink or eliminate the string representation of the
variable.  Here be dragons.

=head2 upd_data

=for ref 

Update the data pointer in a piddle to match its perl SV.

This is useful if you've been monkeying with the packed string
representation of the PDL, which you probably shouldn't be doing
anyway.  (see L<get_dataref|get_dataref>.)

=cut

sub topdl {PDL->topdl(@_)}

####################### Overloaded operators #######################

{ package PDL;
  # use UNIVERSAL 'isa'; # need that later in info function
  use Carp;

  use overload (
		"+"     => \&PDL::plus,     # in1, in2
		"*"     => \&PDL::mult, # in1, in2
		"-"     => \&PDL::minus,    # in1, in2, swap if true
		"/"     => \&PDL::divide,   # in1, in2, swap if true
		
		"+="    => sub { PDL::plus     ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		"*="    => sub { PDL::mult ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		"-="    => sub { PDL::minus    ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		"/="    => sub { PDL::divide   ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true

		">"     => \&PDL::gt,       # in1, in2, swap if true
		"<"     => \&PDL::lt,       # in1, in2, swap if true
		"<="    => \&PDL::le,       # in1, in2, swap if true
		">="    => \&PDL::ge,       # in1, in2, swap if true
		"=="    => \&PDL::eq,       # in1, in2
		"eq"    => \&PDL::eq,       # in1, in2
		"!="    => \&PDL::ne,       # in1, in2
		
		"<<"    => \&PDL::shiftleft,  # in1, in2, swap if true
		">>"    => \&PDL::shiftright, # in1, in2, swap if true
		"|"     => \&PDL::or2,        # in1, in2
		"&"     => \&PDL::and2,       # in1, in2
		"^"     => \&PDL::xor,        # in1, in2
		
		"<<="   => sub { PDL::shiftleft ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		">>="   => sub { PDL::shiftright($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		"|="    => sub { PDL::or2      ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		"&="    => sub { PDL::and2     ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		"^="    => sub { PDL::xor       ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
	        "**="   => sub { PDL::power     ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
	        "%="    => sub { PDL::modulo    ($_[0], $_[1], $_[0], 0); $_[0]; }, # in1, in2, out, swap if true
		
		"sqrt"  => sub { PDL::sqrt ($_[0]); },
		"abs"   => sub { PDL::abs  ($_[0]); },
		"sin"   => sub { PDL::sin  ($_[0]); },
		"cos"   => sub { PDL::cos  ($_[0]); },

		"!"     => sub { PDL::not  ($_[0]); },
		"~"     => sub { PDL::bitnot ($_[0]); },

		"log"   => sub { PDL::log   ($_[0]); },
		"exp"   => sub { PDL::exp   ($_[0]); },

	        "**"    => \&PDL::power,          # in1, in2, swap if true

	        "atan2" => \&PDL::atan2,          # in1, in2, swap if true
	        "%"     => \&PDL::modulo,         # in1, in2, swap if true

	        "<=>"   => \&PDL::spaceship,      # in1, in2, swap if true

		"="     =>  sub {$_[0]},          # Don't deep copy, just copy reference

		".="    => sub {my @args = reverse &PDL::Core::rswap;
# This strange undocumented behavior commented out by CED 18-Mar-2003;
# remove it if you see it in current code after 18-Mar-2004!
#				return $args[1]->info("%C (%A): %T %D %S %M")
#				  if !ref $args[0] && $args[0] eq '';
				PDL::Ops::assgn(@args);
				return $args[1];},
		 
		'x'     =>  sub{my $foo = $_[0]->null();
				  PDL::Primitive::matmult(@_[0,1],$foo); $foo;},

		'bool'  => sub { return 0 if $_[0]->isnull;
				 croak("multielement piddle in conditional expression")
				     unless $_[0]->nelem == 1;
				 $_[0]->clump(-1)->at(0); },
		"\"\""  =>  \&PDL::Core::string   );
}

sub rswap { if($_[2]) { return @_[1,0]; } else { return @_[0,1]; } }

##################### Data type/conversion stuff ########################


# XXX Optimize!

sub PDL::dims {  # Return dimensions as @list
   my $pdl = PDL->topdl (shift);
   my @dims = ();
   for(0..$pdl->getndims()-1) {push @dims,($pdl->getdim($_))}
   return @dims;
}

sub PDL::howbig {
	my $t = shift;
	if("PDL::Type" eq ref $t) {$t = $t->[0]}
	PDL::howbig_c($t);
}

=head2 PDL::threadids

=for ref

Returns the piddle thread IDs as a perl list

Note that C<threadids()> is not exported by default (see example
below for usage). 

=for usage

 use PDL::Core ':Internal'; # use the internal routines of 
                            # the Core module

 @ids = threadids $piddle;

=cut

sub PDL::threadids {  # Return dimensions as @list
   my $pdl = PDL->topdl (shift);
   my @dims = ();
   for(0..$pdl->getnthreadids()) {push @dims,($pdl->getthreadid($_))}
   return @dims;
}

################# Creation/copying functions #######################


sub PDL::pdl { my $x = shift; return $x->new(@_) }

=head2 doflow

=for ref

Turn on/off dataflow

=for usage

 $x->doflow;  doflow($x);

=cut

sub PDL::doflow {
	my $this = shift;
	$this->set_dataflow_f(1);
	$this->set_dataflow_b(1);
}

=head2 flows

=for ref

Whether or not a piddle is indulging in dataflow

=for usage

 something if $x->flows; $hmm = flows($x);

=cut

sub PDL::flows {
 	my $this = shift;
         return ($this->fflows || $this->bflows);
}

=head2 PDL::new

=for ref

new piddle constructor method

=for usage

 $x = PDL->new(SCALAR|ARRAY|ARRAY REF);

=for example

 $x = PDL->new(42);
 $y = new PDL [1..10];

Constructs piddle from perl numbers and lists.	

=cut

sub PDL::new {
   # print "in PDL::new\n";
   my $this = shift;
   return $this->copy if ref($this);
   my $type = ref($_[0]) eq 'PDL::Type' ? ${shift @_}[0]  : $PDL_D;
   my $value = (@_ >1 ? [@_] : shift);  # ref thyself

   unless(defined $value) {
       if($PDL::debug && $PDL::undefval) {
	   print STDERR "Warning: PDL::new converted undef to $PDL::undefval ($PDL::undefval)\n";
       }
       $value = $PDL::undefval+0
   }

   return pdl_avref($value,$this,$type) if ref($value) eq "ARRAY";
   my $new = $this->initialize();
   $new->set_datatype($type);


   if (ref(\$value) eq "SCALAR") {
       $new->setdims([]);
       ${$new->get_dataref}     = pack( $pack[$new->get_datatype], $value );
       $new->upd_data();
   }
   elsif (blessed($value)) { # Object
       $new = $value->copy;
   }
   else {
       barf("Can not interpret argument $value of type ".ref($value) );
   }
   return $new;
}


=head2 copy

=for ref

Make a physical copy of a piddle

=for usage

 $new = $old->copy;

Since C<$new = $old> just makes a new reference, the
C<copy> method is provided to allow real independent
copies to be made.

=cut

# Inheritable copy method
#
# XXX Must be fixed
# Inplace is handled by the op currently.

sub PDL::copy {
    my $value = shift;
    barf("Argument is an ".ref($value)." not an object") unless blessed($value);
    my $option  = shift;
    $option = "" if !defined $option;
    if ($value->is_inplace) {   # Copy protection
       $value->set_inplace(0);
       return $value;
    }
    # threadI(-1,[]) is just an identity vafftrans with threadId copying ;)
    my $new = $value->threadI(-1,[])->sever;
    return $new;
}

=head2 PDL::hdr_copy

=for ref

Return an explicit copy of the header of a PDL.

hdr_copy is just a wrapper for the internal routine _hdr_copy, which
takes the hash ref itself.  That is the routine which is used to make
copies of the header during normal operations if the hdrcpy() flag of
a PDL is set.

General-purpose deep copies are expensive in perl, so some simple
optimization happens:

If the header is a tied array or a blessed hash ref with an associated
method called C<copy>, then that ->copy method is called.  Otherwise, all
elements of the hash are explicitly copied.  References are recursively
deep copied.

This routine seems to leak memory.

=cut

sub PDL::hdr_copy {
  my $pdl = shift;
  my $hdr = $pdl->gethdr;
  return PDL::_hdr_copy($hdr);
}

# Same as hdr_copy but takes a hash ref instead of a PDL.
sub PDL::_hdr_copy {
  my $hdr = shift;
  my $tobj;

  print "called _hdr_copy\n" if($PDL::debug);

  unless( (ref $hdr)=~m/HASH/ ) {
    print"returning undef\n" if($PDL::debug);
    return undef ;
  }

  if($tobj = tied %$hdr) { # 
    print "tied..."if($PDL::debug);
    if(UNIVERSAL::can($tobj,"copy")) {
      my %rhdr;
      tie(%rhdr, ref $tobj, $tobj->copy);
      print "returning\n" if($PDL::debug);
      return \%rhdr;
    }
    
    # Astro::FITS::Header is special for now -- no copy method yet 
    # but it is recognized.  Once it gets a copy method this will become
    # vestigial:

    if(UNIVERSAL::isa($tobj,"Astro::FITS::Header")) {
      print "Astro::FITS::Header..." if($PDL::debug);
      my @cards = $tobj->cards;
      my %rhdr;
      tie(%rhdr,"Astro::FITS::Header", new Astro::FITS::Header(Cards=>\@cards));
      print "returning\n" if($PDL::debug);
      return \%rhdr;
    }
  } 
  elsif(UNIVERSAL::can($hdr,"copy")) {
    print "found a copy method\n" if($PDL::debug);
    return $hdr->copy;
  } 

  # We got here if it's an unrecognized tie or if it's a vanilla hash.
  print "Making a hash copy..." if($PDL::debug);
      
  return PDL::_deep_hdr_copy($hdr);

}

# 
# Sleazy deep-copier that gets most cases 
# --CED 14-April-2003
#

sub PDL::_deep_hdr_copy {
  my $val = shift;
  
  if(ref $val eq 'HASH') {
    my (%a,$key);
    for $key(keys %$val) {
      my $value = $val->{$key};
      $a{$key} = (ref $value) ? PDL::_deep_hdr_copy($value) : $value;
    }
    return \%a;
  } 
  
  if(ref $val eq 'ARRAY') {
    my (@a,$z);
    for $z(@$val) {
      push(@a,(ref $z) ? PDL::_deep_hdr_copy($z) : $z);
    }
    return \@a;
  }
  
  if(ref $val eq 'SCALAR') {
    my $a = $$val;
    return \$a;
  }
  
  if(ref $val eq 'REF') {
    my $a = PDL::_deep_hdr_copy($$val);
    return \$a;
  }
  
  # Special case for PDLs avoids potential nasty header recursion...
  if(UNIVERSAL::isa($val,'PDL')) {
    my $h;
    $val->hdrcpy(0) if($h = $val->hdrcpy); # assignment
    my $out = $val->copy;
    $val->hdrcpy($h) if($h);
    return $out;
  }
  
  if(UNIVERSAL::can($val,'copy')) {
    return $val->copy;
  }

  $val;
}

    
=head2 PDL::unwind

=for ref

Return a piddle which is the same as the argument except
that all threadids have been removed.

=for usage

 $y = $x->unwind;

=head2 PDL::make_physical

=for ref

Make sure the data portion of a piddle can be accessed from XS code.

=for example

 $a->make_physical;
 $a->call_my_xs_method;

Ensures that a piddle gets its own allocated copy of data. This obviously
implies that there are certain piddles which do not have their own data.
These are so called I<virtual> piddles that make use of the I<vaffine>
optimisation (see L<PDL::Indexing|PDL::Indexing>). 
They do not have their own copy of
data but instead store only access information to some (or all) of another
piddle's data.

Note: this function should not be used unless absolutely neccessary
since otherwise memory requirements might be severly increased. Instead
of writing your own XS code with the need to call C<make_physical> you
might want to consider using the PDL preprocessor 
(see L<PDL::PP|PDL::PP>)
which can be used to transparently access virtual piddles without the
need to physicalise them (though there are exceptions).

=cut

sub PDL::unwind {
	my $value = shift;
	my $foo = $value->null();
	$foo .= $value->unthread();
	return $foo;
}

=head2 dummy

=for ref

Insert a 'dummy dimension' of given length (defaults to 1)

No relation to the 'Dungeon Dimensions' in Discworld!

Negative positions specify relative to last dimension,
i.e. C<dummy(-1)> appends one dimension at end,
C<dummy(-2)> inserts a dummy dimension in front of the
last dim, etc.

If you specify a dimension position larger than the existing
dimension list of your PDL, the PDL gets automagically padded with extra
dummy dimensions so that you get the dim you asked for, in the slot you 
asked for.  This could cause you trouble if, for example, 
you ask for $a->dummy(5000,1) because $a will get 5,000 dimensions, 
each of rank 1. 

Because padding at the beginning of the dimension list moves existing
dimensions from slot to slot, it's considered unsafe, so automagic
padding doesn't work for large negative indices -- only for large
positive indices.

=for usage

 $y = $x->dummy($position[,$dimsize]);

=for example

 perldl> p sequence(3)->dummy(0,3)
 [
  [0 0 0]
  [1 1 1]
  [2 2 2]
 ]

 perldl> p sequence(3)->dummy(3,2)
 [
  [
   [0 1 2]
  ]
  [
   [0 1 2]
  ]
 ]

 perldl> p sequence(3)->dummy(-3,2)
 For safety, <pos> < -(dims+1) is not allowed in dummy, allowed min=-2.

=cut

sub PDL::dummy($$;$) {
   my ($pdl,$dim,$size) = @_;
   $dim = $pdl->getndims+1+$dim if $dim < 0;
   $size = 1 unless defined($size);

   barf("For safety, <pos> < -(dims+1) forbidden in dummy.  min="
	 . -($pdl->getndims+1).", pos=". ($dim-1-$pdl->getndims) ) if($dim<0);

   my($s) = ',' x ( ($dim > $pdl->getndims) ? ($pdl->getndims) : ($dim) );
   $s .= '*,' x ( $dim-$pdl->getndims-1 );
   $s .= "*$size";

   $pdl->slice($s);
}  


## Cheesy, slow way
#   while ($dim>$pdl->getndims){
#     print STDERR "."; flush STDERR;
#     $pdl = $pdl->dummy($pdl->getndims,1);
#   }
#
#   barf ("too high/low dimension in call to dummy, allowed min/max=0/"
# 	 . $_[0]->getndims)
#     if $dim>$pdl->getndims || $dim < 0;
#   
#   $_[2] = 1 if ($#_ < 2);
#   $pdl->slice((','x$dim)."*$_[2]");

=head2 clump

=for ref

"clumps" several dimensions into one large dimension

If called with one argument C<$n> clumps the first C<$n>
dimensions into one. For example, if C<$a> has dimensions
C<(5,3,4)> then after

=for example

 $b = $a->clump(2);   # Clump 2 first dimensions

the variable C<$b> will have dimensions C<(15,4)>
and the element C<$b-E<gt>at(7,3)> refers to the element
C<$a-E<gt>at(1,2,3)>.

Use C<clump(-1)> to flatten a piddle. The method L<flat|PDL::Core/flat>
is provided as a convenient alias.  

Clumping with a negative dimension in general leaves that many
dimensions behind -- e.g. clump(-2) clumps all of the first few
dimensions into a single one, leaving a 2-D piddle.

If C<clump> is called with an index list with more than one element
it is treated as a list of dimensions that should be clumped together
into one. The resulting
clumped dim is placed at the position of the lowest index in the list.
This convention ensures that C<clump> does the expected thing in
the usual cases. The following example demonstrates typical usage:

  $a = sequence 2,3,3,3,5; # 5D piddle
  $c = $a->clump(1..3);    # clump all the dims 1 to 3 into one
  print $c->info;          # resulting 3D piddle has clumped dim at pos 1
 PDL: Double D [2,27,5]

=cut

sub PDL::clump {
  my $ndims = $_[0]->getndims;
  if ($#_ < 2) {
    return &PDL::_clump_int($_[0],$_[1]) # Truncate clumping to actual dims
      if $_[1] > $ndims;
    return &PDL::_clump_int(@_);
  } else {
    my ($this,@dims) = @_;
    my $targd = $ndims-1;
    my @dimmark = (0..$ndims-1);
    barf "too many dimensions" if @dims > $ndims;
    for my $dim (@dims) {
      barf "dimension index $dim larger than greatest dimension"
	if $dim > $ndims-1 ;
      $targd = $dim if $targd > $dim;
      barf "duplicate dimension $dim" if $dimmark[$dim]++ > $dim;
    }
    my $clumped = $this->thread(@dims)->unthread(0)->clump(scalar @dims);
    $clumped = $clumped->mv(0,$targd) if $targd > 0;
    return $clumped;
  }
}

=head2 thread_define

=for ref

define functions that support threading at the perl level

=for example

 thread_define 'tline(a(n);b(n))', over {
  line $_[0], $_[1]; # make line compliant with threading
 };


C<thread_define> provides some support for threading (see
L<PDL::Indexing>) at the perl level. It allows you to do things for
which you normally would have resorted to PDL::PP (see L<PDL::PP>);
however, it is most useful to wrap existing perl functions so that the
new routine supports PDL threading.

C<thread_define> is used to define new I<threading aware>
functions. Its first argument is a symbolic repesentation of the new
function to be defined. The string is composed of the name of the new
function followed by its signature (see L<PDL::Indexing> and L<PDL::PP>)
in parentheses. The second argument is a subroutine that will be
called with the slices of the actual runtime arguments as specified by
its signature. Correct dimension sizes and minimal number of
dimensions for all arguments will be checked (assuming the rules of
PDL threading, see L<PDL::Indexing>).

The actual work is done by the C<signature> class which parses the signature
string, does runtime dimension checks and the routine C<threadover> that
generates the loop over all appropriate slices of pdl arguments and creates
pdls as needed.

Similar to C<pp_def> and its C<OtherPars> option it is possible to
define the new function so that it accepts normal perl args as well as
piddles. You do this by using the C<NOtherPars> parameter in the
signature. The number of C<NOtherPars> specified will be passed
unaltered into the subroutine given as the second argument of
C<thread_define>. Let's illustrate this with an example:

 PDL::thread_define 'triangles(inda();indb();indc()), NOtherPars => 2',
  PDL::over {
    ${$_[3]} .= $_[4].join(',',map {$_->at} @_[0..2]).",-1,\n";
  };

This defines a function C<triangles> that takes 3 piddles as input
plus 2 arguments which are passed into the routine unaltered. This routine
is used to collect lists of indices into a perl scalar that is passed by
reference. Each line is preceded by a prefix passed as C<$_[4]>. Here is
typical usage:

 $txt = '';
 triangles(pdl(1,2,3),pdl(1),pdl(0),\$txt," "x10);
 print $txt;

resulting in the following output

 1,1,0,-1,
 2,1,0,-1,
 3,1,0,-1,

which is used in 
L<PDL::Graphics::TriD::VRML|PDL::Graphics::TriD::VRML>
to generate VRML output.

Currently, this is probably not much more than a POP (proof of principle)
but is hoped to be useful enough for some real life work.

Check L<PDL::PP|PDL::PP> for the format of the signature. Currently, the
C<[t]> qualifier and all type qualifiers are ignored.

=cut

sub PDL::over (&) { $_[0] }
sub PDL::thread_define ($$) {
  require PDL::PP::Signature;
  my ($str,$sub) = @_;
  my $others = 0;
  if ($str =~ s/[,]*\s*NOtherPars\s*=>\s*([0-9]+)\s*[,]*//) {$others = $1}
  barf "invalid string $str" unless $str =~ /\s*([^(]+)\((.+)\)\s*$/x;
  my ($name,$sigstr) = ($1,$2);
  print "defining '$name' with signature '$sigstr' and $others extra args\n"
						  if $PDL::debug;
  my $sig = new PDL::PP::Signature($sigstr);
  my $args = @{$sig->names}; # number of piddle arguments
  barf "no piddle args" if $args == 0;
  $args--; 
  # TODO: $sig->dimcheck(@_) + proper creating generation
  my $def = "\@_[0..$args] = map {PDL::Core::topdl(\$_)} \@_[0..$args];\n".
            '$sig->checkdims(@_);
	     PDL::threadover($others,@_,$sig->realdims,$sig->creating,$sub)';
  my $package = caller;
  local $^W = 0; # supress the 'not shared' warnings
  print "defining...\nsub $name { $def }\n" if $PDL::debug;
  eval ("package $package; sub $name { $def }");
  barf "error defining $name: $@\n" if $@;
}

=head2 PDL::thread

=for ref

Use explicit threading over specified dimensions (see also L<PDL::Indexing>)

=for usage

 $b = $a->thread($dim,[$dim1,...])

=for example

 $a = zeroes 3,4,5;
 $b = $a->thread(2,0);

Same as L<PDL::thread1|/PDL::thread1>, i.e. uses thread id 1.

=cut

sub PDL::thread {
	my $var = shift;
	$var->threadI(1,\@_);
}

=head2 diagonal

=for ref

Returns the multidimensional diagonal over the specified dimensions.

=for usage

 $d = $x->diagonal(dim1, dim2,...)

=for example

 perldl> $a = zeroes(3,3,3);
 perldl> ($b = $a->diagonal(0,1))++;
 perldl> p $a
 [
  [
   [1 0 0]
   [0 1 0]
   [0 0 1]
  ]
  [
   [1 0 0]
   [0 1 0]
   [0 0 1]
  ]
  [
   [1 0 0]
   [0 1 0]
   [0 0 1]
  ]
 ]

=cut

sub PDL::diagonal {
	my $var = shift;
	$var->diagonalI(\@_);
}

=head2 PDL::thread1

=for ref

Explicit threading over specified dims using thread id 1.

=for usage

 $xx = $x->thread1(3,1)

=for example

 Wibble

Convenience function interfacing to 
L<PDL::Slices::threadI|PDL::Slices/threadI>.

=cut

sub PDL::thread1 {
	my $var = shift;
	$var->threadI(1,\@_);
}

=head2 PDL::thread2

=for ref

Explicit threading over specified dims using thread id 2.

=for usage

 $xx = $x->thread2(3,1)

=for example

 Wibble

Convenience function interfacing to 
L<PDL::Slices::threadI|PDL::Slices/threadI>.

=cut

sub PDL::thread2 {
	my $var = shift;
	$var->threadI(2,\@_);
}

=head2 PDL::thread3

=for ref

Explicit threading over specified dims using thread id 3.

=for usage

 $xx = $x->thread3(3,1)

=for example

 Wibble

Convenience function interfacing to 
L<PDL::Slices::threadI|PDL::Slices/threadI>.

=cut

sub PDL::thread3 {
	my $var = shift;
	$var->threadI(3,\@_);
}

my %info = (
	    D => {
		  Name => 'Dimension',
		  Sub => \&PDL::Core::dimstr,
		 },
	    T => {
		  Name => 'Type',
		  Sub => sub { return $_[0]->type->shortctype; },
		 },
	    S => {
		  Name => 'State',
		  Sub => sub { my $state = '';
			       $state .= 'P' if $_[0]->allocated;
			       $state .= 'V' if $_[0]->vaffine &&
				 !$_[0]->allocated; # apparently can be both?
			       $state .= '-' if $state eq '';   # lazy eval
			       $state .= 'C' if $_[0]->anychgd;
 			       $state .= 'B' if $_[0]->badflag;
			       $state;
			     },
		 },
	    F => {
		  Name => 'Flow',
		  Sub => sub { my $flows = '';
			       $flows = ($_[0]->bflows ? 'b':'') .
				 '~' . ($_[0]->fflows ? 'f':'')
				   if ($_[0]->flows);
			       $flows;
			     },
		 },
	    M => {
		  Name => 'Mem',
		  Sub => sub { my ($size,$unit) = ($_[0]->allocated ?
						   $_[0]->nelem*
                      PDL::howbig($_[0]->get_datatype)/1024 : 0, 'Kb');
			       if ($size > 0.01*1024) { $size /= 1024;
							$unit = 'Mb' };
			       return sprintf "%6.2f%s",$size,$unit;
			     },
		 },
	    C => {
		  Name => 'Class',
		  Sub => sub { ref $_[0] }
		 },
	    A => {
		  Name => 'Address',
		  Sub => sub { sprintf "%d", $_[0]->address }
		 },
	   );

my $allowed = join '',keys %info;

# print the dimension information about a pdl in some appropriate form
sub dimstr {
  my $this = shift;

  my @dims = $this->dims;
  my @ids  = $this->threadids;
  my ($nids,$i) = ($#ids - 1,0);
  my $dstr = 'D ['. join(',',@dims[0..($ids[0]-1)]) .']';
  if ($nids > 0) {
    for $i (1..$nids) {
      $dstr .= " T$i [". join(',',@dims[$ids[$i]..$ids[$i+1]-1]) .']';
    }
  }
  return $dstr;
}

=head2 sever

=for ref

sever any links of this piddle to parent piddles

In PDL it is possible for a piddle to be just another
view into another piddle's data. In that case we call
this piddle a I<virtual piddle> and the original piddle owning
the data its parent. In other languages these alternate views
sometimes run by names such as I<alias> or I<smart reference>.

Typical functions that return such piddles are C<slice>, C<xchg>,
C<index>, etc. Sometimes, however, you would like to separate the
I<virtual piddle> from its parent's data and just give it a life of
its own (so that manipulation of its data doesn't change the parent).
This is simply achieved by using C<sever>. For example,

=for example

   $a = $pdl->index(pdl(0,3,7))->sever;
   $a++;       # important: $pdl is not modified!

In many (but not all) circumstances it acts therefore similar to 
L<copy|PDL::Core/copy>.
However, in general performance is better with C<sever> and secondly,
C<sever> doesn't lead to futile copying when used on piddles that
already have their own data. On the other hand, if you really want to make
sure to work on a copy of a piddle use L<copy|PDL::Core/copy>.

   $a = zeroes(20);
   $a->sever;   # NOOP since $a is already its own boss!

Again note: C<sever> I<is not> the same as L<copy|PDL::Core/copy>!
For example,

   $a = zeroes(1); # $a does not have a parent, i.e. it is not a slice etc
   $b = $a->sever; # $b is now pointing to the same piddle as $a
   $b++;
   print $a;
 [1]

but

   $a = zeroes(1);
   $b = $a->copy; # $b is now pointing to a new piddle
   $b++;
   print $a;
 [0]


=head2 PDL::info

=for ref

Return formatted information about a piddle.

=for usage

 $x->info($format_string);

=for example

 print $x->info("Type: %T Dim: %-15D State: %S");

Returns a string with info about a piddle. Takes an optional
argument to specify the format of information a la sprintf.
Format specifiers are in the form C<%E<lt>widthE<gt>E<lt>letterE<gt>>
where the width is optional and the letter is one of

=over 7

=item T

Type

=item D

Formatted Dimensions

=item F

Dataflow status

=item S

Some internal flags (P=physical,V=Vaffine,C=changed)

=item C

Class of this piddle, i.e. C<ref $pdl>

=item A

Address of the piddle struct as a unique identifier

=item M

Calculated memory consumption of this piddle's data area

=back

=cut

sub PDL::info {
    my ($this,$str) = @_;
    $str = "%C: %T %D" unless defined $str;
    return ref($this)."->null" 
	if PDL::Core::dimstr($this) =~ /D \[0\]/;
    my @hash = split /(%[-,0-9]*[.]?[0-9]*\w)/, $str;
    my @args = ();
    my $nstr = '';
    for my $form (@hash) {
	if ($form =~ s/^%([-,0-9]*[.]?[0-9]*)(\w)$/%$1s/) {
	    barf "unknown format specifier $2" unless defined $info{$2};
	    push @args, &{$info{$2}->{Sub}}($this);
	}
	$nstr .= $form;
    }
    return sprintf $nstr, @args;
}

=head2 approx

=for ref

test for approximately equal values (relaxed C<==>)

=for example

  # ok if all corresponding values in
  # piddles are within 1e-8 of each other
  print "ok\n" if all approx $a, $b, 1e-8;

C<approx> is a relaxed form of the C<==> operator and
often more appropriate for floating point types (C<float>
and C<double>).

Usage:

=for usage

  $res = approx $a, $b [, $eps]

The optional parameter C<$eps> is remembered across invocations
and initially set to 1e-6, e.g.

  approx $a, $b;         # last $eps used (1e-6 initially)
  approx $a, $b, 1e-10;  # 1e-10
  approx $a, $b;         # also 1e-10

=cut

my $approx = 1e-6;  # a reasonable init value
sub PDL::approx {
  my ($a,$b,$eps) = @_;
  $eps = $approx unless defined $eps;  # the default eps
  $approx = $eps;    # remember last eps
  return ($a-$b)->abs < $eps;
}

=head2 mslice

=for ref

Convenience interface to L<slice|PDL::Slice/slice>, 
allowing easier inclusion of dimensions in perl code.

=for usage

 $a = $x->mslice(...);

=for example

 # below is the same as $x->slice("5:7,:,3:4:2")
 $a = $x->mslice([5,7],X,[3,4,2]);

=cut

# called for colon-less args
# preserves parens if present
sub intpars { $_[0] =~ /\(.*\)/ ? '('.int($_[0]).')' : int $_[0] }

sub PDL::mslice {
        my($pdl) = shift;
        return $pdl->slice(join ',',(map {
                        !ref $_ && $_ eq "X" ? ":" :
			   ref $_ eq "ARRAY" ? $#$_ > 1 && @$_[2] == 0 ? 
			   "(".int(@$_[0]).")" : join ':', map {int $_} @$_ :
                        !ref $_ ? intpars $_ :
                        die "INVALID SLICE DEF $_"
                } @_));
}

=head2 nslice

=for ref

Internally used interface to L<slice|PDL::Slice/slice>
and L<dice|PDL::Slice/dice> that is the runtime part of
the L<PDL::NiceSlice|PDL::NiceSlice> implementation.

=for usage

 $a = $x->nslice(...);

=for example

 # below is the same as $x->slice("5:7,:,3:4:2")
 $a = $x->nslice([5,7],X,[3,4,2]);

It implements a superset of L<mslice|PDL::Core/mslice>'s
features. Should probably not be used in your scripts. Rather
resort to the L<PDL::NiceSlice|PDL::NiceSlice> interface.

=cut

#' get quotes right for emacs

sub _intpar ($) { ref $_[0] ? UNIVERSAL::isa($_[0],'PDL') ?
		$_[0]->nelem == 1 ? $_[0]->flat->at(0) :
		  die "multielement piddle where only one allowed" :
		    die "non piddle ref '".ref $_[0]."'"
		      : ($_[0] =~ s/^\*// ? "*".((int $_[0])||1) : int $_[0]); }
sub PDL::nslice {
  my($pdl) = shift;
  my $h = $pdl->hdrcpy() ? PDL::_hdr_copy($pdl->hdr) : undef;
  my @args = @_;
  my ($i,$noslice) = (0,0);
  for (@args) {
    if (UNIVERSAL::isa($_,'PDL')) {
      if ($_->nelem > 1) {
	if ($_->getndims > 1) {
	  # allow one multi-D arg which will imply flat addressing
	  PDL::Core::barf 'piddle must be <= 1D' if @args > 1;
	  $pdl = $pdl->flat->index($_);
	  $noslice = 1;
	} else {
	  # dice this axis
	  $pdl = $pdl->dice_axis($i,$_);
	  # and keep resulting dim fully in slice
	  $_ = 'X'; 
	}
      } elsif ($_->nelem > 0) # only if piddle is not empty
        { $_ = $_->flat->at(0) } # reduce this one-element piddle
                                      # to a scalar for 'slice'
        else { return $_->copy } # $_ is empty, return empty copy
    }
    $i++;
  }
  unless ($noslice) {
   # print STDERR 'processed arglist: ',join(',',@args);
   my $slstr = join ',',(map {
    !ref $_ && $_ eq "X" ? ":" :
      ref $_ eq "ARRAY" ? $#$_ > 1 && _intpar @$_[2] == 0 ? 
	"("._intpar(@$_[0]).")" : join ':', map {_intpar $_} @$_ :
	  _intpar $_
	} @args);
   # print STDERR "slicestr: $slstr\n";
   $pdl = $pdl->slice($slstr);
  }
  $pdl->sethdr($h) if $h;
  return $pdl;
}

# Utility to determine if argument is blessed object

sub blessed {
    my $ref = ref(shift);
    return $ref =~ /^(REF|SCALAR|ARRAY|HASH|CODE|GLOB||)$/ ? 0 : 1;
}

# Convert numbers to PDL if not already

sub PDL::topdl {
    return $_[1] if blessed($_[1]); # Fall through
    return $_[0]->new($_[1]) if ref(\$_[1]) eq  'SCALAR' or
           ref($_[1]) eq 'ARRAY';
    barf("Can not convert a ".ref($_[1])." to a ".$_[0]);
0;}

# Convert everything to PDL if not blessed

sub alltopdl {
    return $_[1] if blessed($_[1]); # Fall through
    return $_[0]->new($_[1]);
0;}


=head2 inplace

=for ref

Flag a piddle so that the next operation is done 'in place'

=for usage

 somefunc($x->inplace); somefunc(inplace $x);

In most cases one likes to use the syntax C<$y = f($x)>, however
in many case the operation C<f()> can be done correctly
'in place', i.e. without making a new copy of the data for
output. To make it easy to use this, we write C<f()> in such
a way that it operates in-place, and use C<inplace> to hint
that a new copy should be disabled. This also makes for
clear syntax.

Obviously this will not work for all functions, and if in
doubt see the function's documentation. However one
can assume this is
true for all elemental functions (i.e. those which just
operate array element by array element like C<log10>).

=for example

 perldl> $x = xvals zeroes 10;
 perldl> log10(inplace $x)
 perldl> p $x
 [      -Inf 0    0.30103 0.47712125 0.60205999    0.69897
 0.77815125 0.84509804 0.90308999 0.95424251]

=cut

# Flag pdl for in-place operations

sub PDL::inplace {
    my $pdl = PDL->topdl(shift); $pdl->set_inplace(1); return $pdl;
}

# Copy if not inplace


=head2 is_inplace

=for ref

Test the in-place flag on a piddle

=for usage

  $out = ($in->is_inplace) ? $in : zeroes($in);
  $in->set_inplace(0)

Provides access to the L<inplace|/inplace> hint flag, within the perl millieu. 
That way functions you write can be inplace aware... If given an
argument the inplace flag will be set or unset depending on the value
at the same time. Can be used for shortcut tests that delete the
inplace flag while testing:

  $out = ($in->is_inplace(0)) ? $in : zeroes($in); # test & unset!

=head2 set_inplace

=for ref

Set the in-place flag on a piddle

=for usage
  
  $out = ($in->is_inplace) ? $in : zeroes($in);
  $in->set_inplace(0);

Provides access to the L<inplace|/inplace> hint flag, within the perl millieu.
Useful mainly for turning it OFF, as L<inplace|/inplace> turns it ON more
conveniently.

=head2 new_or_inplace

=for ref

Return back either the argument pdl or a copy of it depending on whether
it be flagged in-place or no.  Handy for building inplace-aware functions.

=cut

sub new_or_inplace {
	my $pdl = shift;
	if($pdl->is_inplace) {
		$pdl->set_inplace(0); $pdl;
	} else {
		$pdl->copy();
	}
}
*PDL::new_or_inplace = \&new_or_inplace;

# Allow specifications like zeroes(10,10) or zeroes($x)
# or zeroes(inplace $x) or zeroes(float,4,3)

=head2 PDL::new_from_specification

=for ref

Internal method: create piddle by specification

This is the argument processing method called by L<zeroes|/zeroes>
and some other functions
which constructs piddles from argument lists of the form:

 [type], $nx, $ny, $nz,...

For C<$nx>, C<$ny>, etc. 0 and 1D piddles are allowed.
Giving those has the same effect as if saying C<$arg-E<gt>list>,
e.g.

   1, pdl(5,2), 4

is equivalent to

   1, 5, 2, 4

Note, however, that in all functions using C<new_from_specification>
calling C<func $piddle> will probably not do what you want. So to play safe
use (e.g. with zeroes)

  $pdl = zeroes $dimpdl->list; 

Calling

  $pdl = zeroes $dimpdl;

will rather be equivalent to

  $pdl = zeroes $dimpdl->dims;

However,

  $pdl = zeroes ushort, $dimpdl;

will again do what you intended since it is interpreted
as if you had said

  $pdl = zeroes ushort, $dimpdl->list;

This is unfortunate and confusing but no good solution seems
obvious that would not break existing scripts.

=cut

sub PDL::new_from_specification{
    my $class = shift;
    my $type = ref($_[0]) eq 'PDL::Type' ? ${shift @_}[0]  : $PDL_D;
    my $nelems = 1; my @dims;
    for (@_) {
       if (ref $_) {
         barf "Trying to use non-piddle as dimensions?" unless $_->isa('PDL');
         barf "Trying to use multi-dim piddle as dimensions?"
              if $_->getndims > 1;
         warn "creating > 10 dim piddle (piddle arg)!"
              if $_->nelem > 10;
         for my $dim ($_->list) {$nelems *= $dim; push @dims, $dim}
       } else {
         barf "Dimensions must be positive" if $_<=0;
         $nelems *= $_; push @dims, $_
       }
    }
    my $pdl = $class->initialize();
    $pdl->set_datatype($type);
    $pdl->setdims([@dims]);
    print "Dims: ",(join ',',@dims)," DLen: ",(length $ {$pdl->get_dataref}),"\n" if $PDL::debug;
    return $pdl;
}

# is there such a beast?
# L<PDL::Primitive::isnull|PDL::Primitive/isnull> 
#

=head2 isempty

=for ref

Test whether a piddle is empty

=for usage

 print "The piddle has zero dimension\n" if $pdl->isempty;

This function returns 1 if the piddle has zero elements. This is
useful in particular when using the indexing function which. In the
case of no match to a specified criterion, the returned piddle has
zero dimension.

 perldl> $a=sequence(10)
 perldl> $i=which($a < -1)
 perldl> print "I found no matches!\n" if ($a->isempty);

Note that having zero elements is rather different from the concept
of being a null piddle, see the L<PDL::FAQ|PDL::FAQ> and
L<PDL::Indexing|PDL::Indexing> 
manpages for discussions of this.

=cut 

sub PDL::isempty {
    my $pdl=shift;
    return ($pdl->nelem == 0);
}

=head2 zeroes

=for ref

construct a zero filled piddle from dimension list or template piddle.

Various forms of usage,

(i) by specification or (ii) by template piddle:

=for usage

 # usage type (i):
 $a = zeroes([type], $nx, $ny, $nz,...);
 $a = PDL->zeroes([type], $nx, $ny, $nz,...);
 $a = $pdl->zeroes([type], $nx, $ny, $nz,...);
 # usage type (ii):
 $a = zeroes $b;
 $a = $b->zeroes
 zeroes inplace $a;     # Equivalent to   $a .= 0;
 $a->inplace->zeroes;   #  ""

=for example

 perldl> $z = zeroes 4,3
 perldl> p $z
 [
  [0 0 0 0]
  [0 0 0 0]
  [0 0 0 0]
 ]
 perldl> $z = zeroes ushort, 3,2 # Create ushort array
 [ushort() etc. with no arg returns a PDL::Types token]

See also L<new_from_specification|/new_from_specification>
for details on using piddles in the dimensions list.

=cut

sub zeroes { ref($_[0]) && ref($_[0]) ne 'PDL::Type' ? PDL::zeroes($_[0]) : PDL->zeroes(@_) }
sub PDL::zeroes {
    my $class = shift;
    my $pdl = scalar(@_)? $class->new_from_specification(@_) : $class->new_or_inplace;
    $pdl.=0;
    return $pdl;
}

=head2 ones

=for ref

construct a one filled piddle

=for usage

 $a = ones([type], $nx, $ny, $nz,...);
 etc. (see 'zeroes')

=for example

 see zeroes() and add one

See also L<new_from_specification|/new_from_specification>
for details on using piddles in the dimensions list.

=cut

sub ones { ref($_[0]) && ref($_[0]) ne 'PDL::Type' ? PDL::ones($_[0]) : PDL->ones(@_) }
sub PDL::ones {
    my $class = shift;
    my $pdl = scalar(@_)? $class->new_from_specification(@_) : $class->new_or_inplace;
    $pdl.=1;
    return $pdl;
}

=head2 reshape

=for ref

Change the shape (i.e. dimensions) of a piddle, preserving contents.

=for usage

 $x->reshape(NEWDIMS); reshape($x, NEWDIMS);

The data elements are preserved, obviously they will wrap
differently and get truncated if the new array is shorter.
If the new array is longer it will be zero-padded.

***Potential incompatibility with earlier versions of PDL****
If the list of C<NEWDIMS> is empty C<reshape> will just drop
all dimensions of size 1 (preserving the number of elements):

  $a = sequence(3,4,5);
  $b = $a(1,3);
  $b->reshape();
  print $b->info;
 PDL: Double D [5]

Dimensions of size 1 will also be dropped if C<reshape> is
invoked with the argument -1:

  $b = $a->reshape(-1);

As opposed to C<reshape> without arguments, C<reshape(-1)>
preserves dataflow:

  $a = ones(2,1,2);
  $b = $a(0)->reshape(-1);
  $b++;
  print $a;
 [
  [
   [2 1]
  ]
  [
   [2 1]
  ]
 ]

Note: an explicit copy of slices is generally forced - this is the
only way (for now) of stopping a crash if C<$x> is a slice.
Important: Physical piddles are changed inplace!

=for example

 perldl> $x = sequence(10)
 perldl> reshape $x,3,4; p $x
 [
  [0 1 2]
  [3 4 5]
  [6 7 8]
  [9 0 0]
 ]
 perldl> reshape $x,5; p $x
 [0 1 2 3 4]

=cut

*reshape = \&PDL::reshape;
sub PDL::reshape{
  if (@_ == 2 && $_[1] == -1) {  # a slicing reshape that drops 1-dims
    return $_[0]->slice(join(',',map {$_ == 1 ? '(0)' : ''} $_[0]->dims));
  }
  my $pdl = pdl($_[0]);
  my $nelem = $pdl->nelem;
  my @dims = @_[1..$#_];
  for my $dim(@dims) { barf "reshape: invalid dim size '$dim'" if $dim < 0 }
  @dims = grep($_ != 1, $pdl->dims) if @dims == 0; # get rid of dims of size 1
  $pdl->setdims([@dims]);
  $pdl->upd_data;
  if ($pdl->nelem > $nelem) {
     my $tmp=$pdl->clump(-1)->slice("$nelem:-1");
     $tmp .= 0;
  }
  $_[0] = $pdl;
  return $pdl;
}

=head2 squeeze

=for ref

eliminate all singleton dimensions (dims of size 1)

=for example

 $b = $a(0,0)->squeeze;

Alias for C<reshape(-1)>. Removes all singleton dimensions
and preserves dataflow. A more concise interface is
provided by L<PDL::NiceSlice|PDL::NiceSlice> via modifiers:

 use PDL::NiceSlice;
 $b = $a(0,0;-); # same as $a(0,0)->squeeze

=cut

*squeeze = \&PDL::squeeze;
sub PDL::squeeze { return $_[0]->reshape(-1) }

=head2 flat

=for ref

flatten a piddle (alias for C<$pdl->clump(-1)>)

=for example

  $srt = $pdl->flat->qsort;

Useful method to make a 1D piddle from an
arbitrarily sized input piddle. Data flows
back and forth as usual with slicing routines.
Falls through if argument already E<lt>= 1D.

=cut

*flat = \&PDL::flat;
sub PDL::flat { # fall through if < 2D
  return $_[0]->getndims != 1 ? $_[0]->clump(-1) : $_[0];
}

=head2 convert

=for ref

Generic datatype conversion function

=for usage

 $y = convert($x, $newtype);

=for example

 $y = convert $x, long
 $y = convert $x, ushort

C<$newtype> is a type number, for convenience they are
returned by C<long()> etc when called without arguments.

=cut

# type to type conversion functions (with automatic conversion to pdl vars)

sub PDL::convert {
  # we don't allow inplace conversion at the moment
  # (not sure what needs to be changed)
  barf 'Usage: $y = convert($x, $newtype)'."\n" if $#_!=1;
  my ($pdl,$type)= @_;
  $pdl = pdl($pdl) unless ref $pdl; # Allow normal numbers
  $type = $type->enum if ref($type) eq 'PDL::Type';
  return $pdl if $pdl->get_datatype == $type;
  # make_physical-call: temporary stopgap to work around core bug
  my $conv = $pdl->flowconvert($type)->make_physical->sever;
  return $conv;
}

=head2 Datatype_conversions

=for ref

byte|short|ushort|long|longlong|float|double convert shorthands

=for usage

 $y = double $x; $y = ushort [1..10];
 # all of byte|short|ushort|long|float|double behave similarly

When called with a piddle argument, they convert to the specific
datatype.

When called with a numeric or list / listref argument they construct
a new piddle. This is a convenience to avoid having to be
long-winded and say C<$x = long(pdl(42))>

Thus one can say:

 $a = float(1,2,3,4);           # 1D
 $a = float([1,2,3],[4,5,6]);   # 2D
 $a = float([[1,2,3],[4,5,6]]); # 2D

Note the last two are equivalent - a list is automatically
converted to a list reference for syntactic convenience. i.e. you
can omit the outer C<[]>

When called with no arguments return a special type token.
This allows syntactical sugar like:

 $x = ones byte, 1000,1000;

This example creates a large piddle directly as byte datatype in
order to save memory.

In order to control how undefs are handled in converting from perl lists to
PDLs, one can set the variable C<$PDL::undefval>;
see the function L<pdl()|/pdl> for more details.

=for example

 perldl> p $x=sqrt float [1..10]
 [1 1.41421 1.73205 2 2.23607 2.44949 2.64575 2.82843 3 3.16228]
 perldl> p byte $x
 [1 1 1 2 2 2 2 2 3 3]

=cut


=head2 byte

=for ref

Convert to byte datatype - see 'Datatype_conversions'

=cut


=head2 short

=for ref

Convert to short datatype - see 'Datatype_conversions'

=cut


=head2 ushort

=for ref

Convert to ushort datatype - see 'Datatype_conversions'

=cut


=head2 long

=for ref

Convert to long datatype - see 'Datatype_conversions'

=cut


=head2 longlong

=for ref

Convert to longlong datatype - see 'Datatype_conversions'

=cut


=head2 float

=for ref

Convert to float datatype - see 'Datatype_conversions'

=cut


=head2 double

=for ref

Convert to double datatype - see 'Datatype_conversions'

=cut

for (
['byte',0],
['short',1],
['ushort',2],
['long',3],
['longlong',4],
['float',5],
['double',6]
) {
	eval ('sub PDL::'.$_->[0]." { ".
		'return bless ['.$_->[1].'], "PDL::Type" unless @_;
                convert(alltopdl(\'PDL\', (scalar(@_)>1 ? [@_] : shift)),'.$_->[1].')
		}');
}

=head2 type

=for ref

return the type of a piddle as a blessed type object

A convenience function for use with the piddle constructors, e.g.

=for example

 $b = PDL->zeroes($a->type,$a->dims,3);
 die "must be float" unless $a->type == float;

See also the discussion of the C<PDL::Type> class in L<PDL::Types>.
Note that the C<PDL::Type> objects have overloaded comparison and
stringify operators so that you can compare and print types:

 $a = $a->float if $a->type < float;
 $t = $a->type; print "Type is $t\";

=cut

sub PDL::type { return PDL::Type->new($_[0]->get_datatype); }

##################### Printing ####################

# New string routine

$PDL::_STRINGIZING = 0;

sub PDL::string {
    my($self,$format)=@_;
    if($PDL::_STRINGIZING) {
    	return "ALREADY_STRINGIZING_NO_LOOPS";
    }
    local $PDL::_STRINGIZING = 1;
    my $ndims = $self->getndims;
    if($self->nelem > 10000) {
    	return "TOO LONG TO PRINT";
    }
    if ($ndims==0) {
	if ( $self->badflag() and $self->isbad() ) {
	    return "BAD";
	} else {
	    my @x = $self->at();
	    return ($format ? sprintf($format, $x[0]) : "$x[0]");
	}
    }
    return "Null" if $self->isnull;
    return "Empty" if $self->isempty; # Empty piddle
    local $sep  = $PDL::use_commas ? "," : " ";
    local $sep2 = $PDL::use_commas ? "," : "";
    if ($ndims==1) {
       return str1D($self,$format);
    }
    else{
       return strND($self,$format,0);
    }
}

############## Section/subsection functions ###################

=head2 list

=for ref

Convert piddle to perl list

=for usage

 @tmp = list $x;

Obviously this is grossly inefficient for the large datasets PDL is designed to
handle. This was provided as a get out while PDL matured. It  should now be mostly
superseded by superior constructs, such as PP/threading. However it is still
occasionally useful and is provied for backwards compatibility.

=for example

 for (list $x) {
   # Do something on each value...
 }

=cut

# No threading, just the ordinary dims.
sub PDL::list{ # pdl -> @list
     barf 'Usage: list($pdl)' if $#_!=0;
     my $pdl = PDL->topdl(shift);
     return () if nelem($pdl)==0;
     @{listref_c($pdl)};
}

=head2 listindices

=for ref

Convert piddle indices to perl list

=for usage

 @tmp = listindices $x;

C<@tmp> now contains the values C<0..nelem($x)>.

Obviously this is grossly inefficient for the large datasets PDL is designed to
handle. This was provided as a get out while PDL matured. It  should now be mostly
superseded by superior constructs, such as PP/threading. However it is still
occasionally useful and is provied for backwards compatibility.

=for example

 for $i (listindices $x) {
   # Do something on each value...
 }

=cut

sub PDL::listindices{ # Return list of index values for 1D pdl
     barf 'Usage: list($pdl)' if $#_!=0;
     my $pdl = shift;
     return () if nelem($pdl)==0;
     barf 'Not 1D' if scalar(dims($pdl)) != 1;
     return (0..nelem($pdl)-1);
}

=head2 set

=for ref

Set a single value inside a piddle

=for usage

 set $piddle, @position, $value

C<@position> is a coordinate list, of size equal to the
number of dimensions in the piddle. Occasionally useful,
mainly provided for backwards compatibility as superseded
by use of L<slice|PDL::Slices/slice> and assigment operator C<.=>.

=for example

 perldl> $x = sequence 3,4
 perldl> set $x, 2,1,99
 perldl> p $x
 [
  [ 0  1  2]
  [ 3  4 99]
  [ 6  7  8]
  [ 9 10 11]
 ]

=cut

sub PDL::set{    # Sets a particular single value
    barf 'Usage: set($pdl, $x, $y,.., $value)' if $#_<2;
    my $self  = shift; my $value = pop @_;
    set_c ($self, [@_], $value);
    return $self;
}

=head2 at

=for ref

Returns a single value inside a piddle as perl scalar.

=for usage

 $z = at($piddle, @position); $z=$piddle->at(@position);

C<@position> is a coordinate list, of size equal to the
number of dimensions in the piddle. Occasionally useful
in a general context, quite useful too inside PDL internals.

=for example

 perldl> $x = sequence 3,4
 perldl> p $x->at(1,2)
 7

=cut

sub PDL::at {     # Return value at ($x,$y,$z...)
    barf 'Usage: at($pdl, $x, $y, ...)' if $#_<0;
    my $self = shift;
    at_bad_c ($self, [@_]);
}

=head2 sclr

=for ref

return a single value from a piddle as a scalar

=for example

  $val = $a(10)->sclr;
  $val = sclr inner($a,$b);

The C<sclr> method is useful to turn a piddle into a normal Perl
scalar. Its main advantage over using C<at> for this purpose is the fact
that you do not need to worry if the piddle is 0D, 1D or higher dimensional.
Using C<at> you have to supply the correct number of zeroes, e.g.

  $a = sequence(10);
  $b = $a->slice('4');
  print $b->sclr; # no problem
  print $b->at(); # error: needs at least one zero

C<sclr> is generally used when a Perl scalar is required instead
of a one-element piddle. If the input is a multielement piddle
the first value is returned as a Perl scalar. You can optionally
switch on checks to ensure that the input piddle has only one element:

  PDL->sclr({Check => 'warn'}); # carp if called with multi-el pdls
  PDL->sclr({Check => 'barf'}); # croak if called with multi-el pdls

are the commands to switch on warnings or raise an error if
a multielement piddle is passed as input. Note that these options
can only be set when C<sclr> is called as a class method (see
example above). Use

  PDL->sclr({Check=>0});

to switch these checks off again (default setting);
When called as a class method the resulting check mode is returned
(0: no checking, 1: warn, 2: barf).

=cut

my $chkmode = 0; # default mode no checks
use Carp;
use PDL::Options;
sub PDL::sclr {
  my $this = shift;
  if (ref $this) { # instance method
    carp "multielement piddle in 'sclr' call"
      if ($chkmode == 1 && $this->nelem > 1);
    croak "multielement piddle in 'sclr' call"
      if ($chkmode == 2 && $this->nelem > 1);
    return sclr_c($this);
  } else {  # class method
    my $check = (iparse({Check=>0},ifhref($_[0])))[1];
    if (lc($check) eq 'warn') {$chkmode = 1}
    elsif (lc($check) eq 'barf') {$chkmode = 2}
    else {$chkmode = $check != 0 ? 1 : 0}
    return $chkmode;
  }
}

=head2 cat

=for ref

concatentate piddles to N+1 dimensional piddle

Takes a list of N piddles of same shape as argument,
returns a single piddle of dimension N+1

=for example

 perldl> $x = cat ones(3,3),zeroes(3,3),rvals(3,3); p $x
 [
  [
   [1 1 1]
   [1 1 1]
   [1 1 1]
  ]
  [
   [0 0 0]
   [0 0 0]
   [0 0 0]
  ]
  [
   [1 1 1]
   [1 0 1]
   [1 1 1]
  ]
 ]

=cut

sub PDL::cat {
  my $res = $_[0]->initialize; $res->set_datatype($_[0]->get_datatype);
  $res->setdims([$_[0]->dims,scalar(@_)]);
  my ($i,$t); my $s = ":,"x$_[0]->getndims;
  for (@_) { $t = $res->slice($s."(".$i++.")"); $t .= $_}

   # propogate any bad flags
   for (@_) { if ( $_->badflag() ) { $res->badflag(1); last; } }

  return $res;
}

=head2 dog

=for ref

Opposite of 'cat' :). Split N dim piddle to list of N-1 dim piddles

Takes a single N-dimensional piddle and splits it into a list of N-1 dimensional
piddles. The breakup is done along the last dimension.
Note the dataflown connection is still preserved by default,
e.g.:

=for example

 perldl> $p = ones 3,3,3
 perldl> ($a,$b,$c) = dog $p
 perldl> $b++; p $p
 [
  [
   [1 1 1]
   [1 1 1]
   [1 1 1]
  ]
  [
   [2 2 2]
   [2 2 2]
   [2 2 2]
  ]
  [
   [1 1 1]
   [1 1 1]
   [1 1 1]
  ]
 ]

=for options

 Break => 1   Break dataflow connection (new copy)

=cut

sub PDL::dog {
  my $opt = pop @_ if ref($_[-1]) eq 'HASH';
  my $p = shift;
  my @res; my $s = ":,"x($p->getndims-1);
  for my $i (0..$p->getdim($p->getndims-1)-1) {
     $res[$i] = $p->slice($s."(".$i.")");
     $res[$i] = $res[$i]->copy if $$opt{Break};
     $i++;
  }
  return @res;
}

# New error handling routine

=head2 barf

=for ref

Standard error reporting routine for PDL.

C<barf()> is the routine PDL modules should call to report errors. This
is because C<barf()> will report the error as coming from the correct
line in the module user's script rather than in the PDL module.

It does this magic by unwinding the stack frames until it reaches
a package NOT beginning with C<"PDL::">. If you DO want it to report
errors in some module PDL::Foo (e.g. when debugging PDL::Foo) then
set the variable C<$PDL::Foo::Debugging=1>.

Additionally if you set the variable C<$PDL::Debugging=1> you will
get a COMPLETE stack trace back up to the top level package.

Finally C<barf()> will try and report usage information from the
PDL documentation database if the error message is of the
form 'Usage: func'.

Remember C<barf()> is your friend. *Use* it!

=for example

At the perl level:

 barf("User has too low an IQ!");

In C or XS code:

 barf("You have made %d errors", count);

Note: this is one of the few functions ALWAYS exported
by PDL::Core

=cut

 sub barf { die barf_msg(@_) };
use Carp;
#sub barf { croak barf_msg(@_) };

# This sub is called by Perl barf() and pdl_barf in pdlcore.c

sub barf_msg {
  my ($err) = @_;
  my $i = 0;
  my($pack,$file,$line);
  my $msg="";
  $msg .= "PDL: $err\nStack trace:\n" if $PDL::Debugging;
  while(1) { # Unwind the stack
    ($pack,$file,$line) = caller($i);
    last unless $pack;
    $msg .= " Level $i: file $file, line $line, pkg $pack\n" if $PDL::Debugging;
    last if !$PDL::Debugging and ($pack !~ /^PDL::|^PDL$/ or eval '$'.$pack."::Debugging");
    $i++;
  }

  if ($err =~ /^Usage:\s+(PDL.*::)_(\w+)_int/ or $err =~ /^Usage:\s+(PDL.*::)?\s*(\w+)/) {
     local $match = $2;
     eval << "EOD";
     \$msg .= "PDL: incorrect usage of function '$match()'\nFile $file, line $line, pkg $pack\n" if \$pack;
     \$msg .= "Usage information from PDL docs database:\n";
     use PDL::Doc::Perldl;
     \$msg .= PDL::Doc::Perldl::usage_string ('$match');
EOD
  }
  else{
     $msg .= "PDL: $err\nCaught at file $file, line $line, pkg $pack\n" if $pack;
  }
  $msg .= "\n" if substr($msg,-1,1) ne "\n";
  return $msg;
}

###################### Misc internal routines ####################


# Recursively pack an N-D array ref in format [[1,1,2],[2,2,3],[2,2,2]] etc
# package vars $level and @dims must be initialised first.

sub rpack {
    my ($ptype,$a) = @_;  my ($ret,$type);

    $ret = "";
    if (ref($a) eq "ARRAY") {

       if (defined($dims[$level])) {
           barf 'Array is not rectangular' unless $dims[$level] == scalar(@$a);
       }else{
          $dims[$level] = scalar(@$a);
       }

       $type = ref($$a[0]);
        if ($type) {
        $level++;
        for(@$a) {
            barf 'Array is not rectangular' unless $type eq ref($_); # Equal types
            $ret .= rpack($ptype,$_);
        }
        $level--;
        } else {
        # These are leaf nodes
        $ret = pack $ptype, map {defined($_) ? $_ : $PDL::undefval} @$a;
      }
    } elsif (ref($a) eq "PDL") {
	barf 'Cannot make a new piddle from two or more piddles, try "cat"';
    } else {
        barf "Don't know how to make a PDL object from passed argument";
    }
    return $ret;
}

sub rcopyitem {        # Return a deep copy of an item - recursively
    my $x = shift;
    my ($y, $key, $value);
    if (ref(\$x) eq "SCALAR") {
       return $x;
    }elsif (ref($x) eq "SCALAR") {
       $y = $$x; return \$y;
    }elsif (ref($x) eq "ARRAY") {
       $y = [];
       for (@$x) {
           push @$y, rcopyitem($_);
       }
       return $y;
    }elsif (ref($x) eq "HASH") {
       $y={};
       while (($key,$value) = each %$x) {
          $$y{$key} = rcopyitem($value);
       }
       return $y;
    }elsif (blessed($x)) {
       return $x->copy;
    }else{
       barf ('Deep copy of object failed - unknown component with type '.ref($x));
    }
0;}

# N-D array stringifier

sub strND {
    my($self,$format,$level)=@_;
#    $self->make_physical();
    my @dims = $self->dims;
    # print "STRND, $#dims\n";

    if ($#dims==1) { # Return 2D string
       return str2D($self,$format,$level);
    }
    else { # Return list of (N-1)D strings
       my $secbas = join '',map {":,"} @dims[0..$#dims-1];
       my $ret="\n"." "x$level ."["; my $j;
       for ($j=0; $j<$dims[$#dims]; $j++) {
       	   my $sec = $secbas . "($j)";
#	   print "SLICE: $sec\n";

           $ret .= strND($self->slice($sec),$format, $level+1);
	   chop $ret; $ret .= $sep2;
       }
       chop $ret if $PDL::use_commas;
       $ret .= "\n" ." "x$level ."]\n";
       return $ret;
    }
}


# String 1D array in nice format

sub str1D {
    my($self,$format)=@_;
    barf "Not 1D" if $self->getndims()!=1;
    my $x = listref_c($self);
    my ($ret,$dformat,$t);
    $ret = "[";
    my $dtype = $self->get_datatype();
    $dformat = $PDL::floatformat  if $dtype == $PDL_F;
    $dformat = $PDL::doubleformat if $dtype == $PDL_D;

    my $badflag = $self->badflag();
    for $t (@$x) {
	if ( $badflag and $t eq "BAD" ) {
	    # do nothing
        } elsif ($format) {
	  $t = sprintf $format,$t;
	} else{ # Default
	    if ($dformat && length($t)>7) { # Try smaller
		$t = sprintf $dformat,$t;
	    }
	}
       $ret .= $t.$sep;
    }

    chop $ret; $ret.="]";
    return $ret;
}

# String 2D array in nice uniform format

sub str2D{
    my($self,$format,$level)=@_;
#    print "STR2D:\n"; $self->printdims();
    my @dims = $self->dims();
    barf "Not 2D" if scalar(@dims)!=2;
    my $x = listref_c($self);
    my ($i, $f, $t, $len, $ret);

    my $dtype = $self->get_datatype();
    my $badflag = $self->badflag();

    my $findmax = 1;
    if (!defined $format || $format eq "") { 
	# Format not given? - find max length of default
	$len=0;

	if ( $badflag ) {
	    for (@$x) { 
		if ( $_ eq "BAD" ) { $i = 3; } 
		else               { $i = length($_); }
		$len = $i>$len ? $i : $len;
	    } 
	} else {
	    for (@$x) {$i = length($_); $len = $i>$len ? $i : $len };
	}

	$format = "%".$len."s";
	
	if ($len>7) { # Too long? - perhaps try smaller format
	    if ($dtype == $PDL_F) {
		$format = $PDL::floatformat;
	    } elsif ($dtype == $PDL_D) {
		$format = $PDL::doubleformat;
	    } else {
		# Stick with default
		$findmax = 0;
	    }
	}
	else {
	    # Default ok
	    $findmax = 0;
	}
    }

    if($findmax) {
	# Find max length of strings in final format
	$len=0;

	if ( $badflag ) {
	    for (@$x) {
		if ( $_ eq "BAD" ) { $i = 3; }
		else               { $i = length(sprintf $format,$_); }
		$len = $i>$len ? $i : $len;
	    }
	} else {
	    for (@$x) {
		$i = length(sprintf $format,$_); $len = $i>$len ? $i : $len;
	    }
	}
    } # if: $findmax

    $ret = "\n" . " "x$level . "[\n";
    { 
	my $level = $level+1;
	$ret .= " "x$level ."[";
	for ($i=0; $i<=$#$x; $i++) {

	    if ( $badflag and $$x[$i] eq "BAD" ) {
		$f = "BAD";
	    } else {
		$f = sprintf $format,$$x[$i];
	    }

	    $t = $len-length($f); $f = " "x$t .$f if $t>0;
	    $ret .= $f;
	    if (($i+1)%$dims[0]) {
		$ret.=$sep;
	    }
	    else{ # End of output line
		$ret.="]";
		if ($i==$#$x) { # very last number
		    $ret.="\n";
		}
		else{
		    $ret.= $sep2."\n" . " "x$level ."[";
		}
	    }
	}
    }
    $ret .= " "x$level."]\n";
    return $ret;
}


#
# Sleazy hcpy saves me time typing
#
sub PDL::hcpy {
  $_[0]->hdrcpy($_[1]);
  $_[0];
}

########## Docs for functions in Core.xs ##################
# Pod docs for functions that are imported from Core.xs and are
#  not documented elsewhere. Currently this is not a complete
#  list. There are others.

=head2 gethdr

=for ref

Retrieve header information from a piddle

=for example

 $pdl=rfits('file.fits');
 $h=$pdl->gethdr;
 print "Number of pixels in the X-direction=$$h{NAXIS1}\n";

The C<gethdr> function retrieves whatever header information is contained
within a piddle. The header can be set with L<sethdr|/sethdr> and is always a 
hash reference or undef.

C<gethdr> returns undef if the piddle has not yet had a header
defined; compare with C<hdr> and C<fhdr>, which are guaranteed to return a 
defined value.

Note that gethdr() works by B<reference>: you can modify the header
in-place once it has been retrieved:

  $a  = rfits($filename);
  $ah = $a->gethdr();
  $ah->{FILENAME} = $filename;

It is also important to realise that in most cases the header is not
automatically copied when you copy the piddle.  See L<hdrcpy|/hdrcpy>
to enable automatic header copying.  

Here's another example: a wrapper around rcols that allows your piddle
to remember the file it was read from and the columns could be easily
written (here assuming that no regexp is needed, extensions are left
as an exercise for the reader)

 sub ext_rcols {
    my ($file, @columns)=@_;
    my $header={};
    $$header{File}=$file;
    $$header{Columns}=\@columns;

    @piddles=rcols $file, @columns;
    foreach (@piddles) { $_->sethdr($header); } 
    return @piddles;
 }

=head2 hdr

=for ref

Retrieve or set header information from a piddle

=for example

 $pdl->hdr->{CDELT1} = 1;

The C<hdr> function allows convenient access to the header of a
piddle.  Unlike C<gethdr> it is guaranteed to return a defined value,
so you can use it in a hash dereference as in the example.  If the
header does not yet exist, it gets autogenerated as an empty hash. 

Note that this is usually -- but not always -- What You Want.  If you
want to use a tied L<Astro::FITS::Header|Astro::FITS::Header> hash,
for example, you should either construct it yourself and use C<sethdr>
to put it into the piddle, or use L<fhdr|fhdr> instead.  (Note that
you should be able to write out the FITS file successfully regardless
of whether your PDL has a tied FITS header object or a vanilla hash).

=head2 fhdr

=for ref

Retrieve or set FITS header information from a piddle

=for example

 $pdl->fhdr->{CDELT1} = 1;

The C<fhdr> function allows convenient access to the header of a
piddle.  Unlike C<gethdr> it is guaranteed to return a defined value,
so you can use it in a hash dereference as in the example.  If the
header does not yet exist, it gets autogenerated as a tied 
L<Astro::FITS::Header|Astro::FITS::Header> hash.  

Astro::FITS::Header tied hashes are better at matching the behavior of
FITS headers than are regular hashes.  In particular, the hash keys
are CAsE INsEnSItiVE, unlike normal hash keys.  See
L<Astro::FITS::Header> for details.

If you do not have Astro::FITS::Header installed, you get back a 
normal hash instead of a tied object.  

=head2 sethdr

=for ref

Set header information of a piddle

=for example

 $pdl = zeroes(100,100);
 $h = {NAXIS=>2, NAXIS1=>100, NAXIS=>100, COMMENT=>"Sample FITS-style header"};
 # add a FILENAME field to the header
 $$h{FILENAME} = 'file.fits';
 $pdl->sethdr( $h );

The C<sethdr> function sets the header information for a piddle.
You must feed in a hash ref or undef, and the header field of the PDL is 
set to be a new ref to the same hash (or undefined).  

The hash ref requirement is a speed bump put in place since the normal
use of headers is to store fits header information and the like.  Of course,
if you want you can hang whatever ugly old data structure you want off
of the header, but that makes life more complex.

Remember that the hash is not copied -- the header is made into a ref
that points to the same underlying data.  To get a real copy without
making any assumptions about the underlying data structure, you
can use one of the following:

  use PDL::IO::Dumper;
  $pdl->sethdr( deep_copy($h) );

(which is slow but general), or 
 
  $pdl->sethdr( PDL::_hdr_copy($h) )
 
(which uses the built-in sleazy deep copier), or (if you know that all
the elements happen to be scalars):

  { my %a = %$h;
    $pdl->sethdr(\%a);
  }

which is considerably faster but just copies the top level.

The C<sethdr> function must be given a hash reference or undef.  For
further information on the header, see L<gethdr|/gethdr>, L<hdr|/hdr>,
L<fhdr|/fhdr> and L<hdrcpy|/hdrcpy>.

=head2 hdrcpy

=for ref

switch on/off/examine automatic header copying

=for example

 print "hdrs will be copied" if $a->hdrcpy;
 $a->hdrcpy(1);       # switch on automatic header copying 
 $b = $a->sumover;    # and $b will inherit $a's hdr
 $a->hdrcpy(0);       # and now make $a non-infectious again

C<hdrcpy> without an argument just returns the current setting of the
flag.  See also "hcpy" which returns its PDL argument (and so is useful
in method-call pipelines).

Normally, the optional header of a piddle is not copied automatically
in pdl operations. Switching on the hdrcpy flag using the C<hdrcpy>
method will enable automatic hdr copying. Note that an actual deep
copy gets made, which is rather processor-inefficient -- so avoid 
using header copying in tight loops!

Most PDLs have the C<hdrcpy> flag cleared by default; however, some
routines (notably L<rfits|PDL::IO::FITS/rfits>) set it by default
where that makes more sense.

The C<hdrcpy> flag is viral: if you set it for a PDL, then derived
PDLs will get copies of the header and will also have their C<hdrcpy>
flags set.  For example:

  $a = xvals(50,50);
  $a->hdrcpy(1);
  $a->hdr->{FOO} = "bar";
  $b = $a++;
  $c = $b++;
  print $b->hdr->{FOO}, " - ", $c->hdr->{FOO}, "\n";
  $b->hdr->{FOO} = "baz";
  print $a->hdr->{FOO}, " - ", $b->hdr->{FOO}, " - ", $c->hdr->{FOO}, "\n";

will print:

  bar - bar
  bar - baz - bar

=head2 hcpy

=for ref

Switch on/off automatic header copying, with PDL pass-through

=for example
  
  $a = rfits('foo.fits')->hcpy(0);
  $a = rfits('foo.fits')->hcpy(1);

C<hcpy> sets or clears the hdrcpy flag of a PDL, and returns the PDL
itself.  That makes it convenient for inline use in expressions.


=head1 AUTHOR

Copyright (C) Karl Glazebrook (kgb@aaoepp.aao.gov.au),
Tuomas J. Lukka, (lukka@husc.harvard.edu) and Christian
Soeller (c.soeller@auckland.ac.nz) 1997.
Modified, Craig DeForest (deforest@boulder.swri.edu) 2002.
All rights reserved. There is no warranty. You are allowed
to redistribute this software / documentation under certain
conditions. For details, see the file COPYING in the PDL
distribution. If this file is separated from the PDL distribution,
the copyright notice should be included in the file.

=cut


#
# Easier to implement in perl than in XS...
#   -- CED
#

sub PDL::fhdr {
    my $pdl = shift;

    return $pdl->hdr
	if( (defined $pdl->gethdr) ||
	!defined $Astro::FITS::Header::VERSION
	    );
	
    # Avoid bug in 1.15 and earlier Astro::FITS::Header
    my @hdr = ("SIMPLE  =                    T");
    my $hdr = new Astro::FITS::Header(Cards=>\@hdr);
    tie my %hdr, "Astro::FITS::Header", $hdr;
    $pdl->sethdr(\%hdr);
    return \%hdr;
}
    
	

1;# Exit with OK status

