NAME

PDL::Types - define fundamental PDL Datatypes

SYNOPSIS

use PDL::Types;

$pdl = ushort( 2.0, 3.0 );
print "The actual c type used to store ushort's is '" .
   $pdl->type->realctype() . "'\n";
The actual c type used to store ushort's is 'unsigned short'

DESCRIPTION

Internal module - holds all the PDL Type info. The type info can be accessed easily using the PDL::Type object returned by the type method as shown in the synopsis.

Skip to the end of this document to find out how to change the set of types supported by PDL.

FUNCTIONS

A number of functions are available for module writers to get/process type information. These are used in various places (e.g. PDL::PP, PDL::Core) to generate the appropriate type loops, etc.

typesrtkeys

Returns an array of keys of typehash sorted in order of type complexity

pdl> @typelist = PDL::Types::typesrtkeys;
pdl> print @typelist;
PDL_SB PDL_B PDL_S PDL_US PDL_L PDL_UL PDL_IND PDL_ULL PDL_LL PDL_F PDL_D PDL_LD PDL_CF PDL_CD PDL_CLD

ppdefs

Returns an array of pp symbols for all real types. This informs the default GenericTypes for pp_def functions, making support for complex types require an "opt-in".

pdl> print PDL::Types::ppdefs
A B S U L K N P Q F D E

ppdefs_complex

Returns an array of pp symbols for all complex types.

pdl> print PDL::Types::ppdefs_complex
G C H

ppdefs_all

Returns an array of pp symbols for all types including complex.

pdl> print PDL::Types::ppdefs_all
A B S U L K N P Q F D E G C H

typesynonyms

return type related synonym definitions to be included in pdl.h . This routine must be updated to include new types as required. Mostly the automatic updating should take care of the vital things.

PDL TYPES OVERVIEW

As of 2.065, PDL supports these types:

SByte

Signed 8-bit value.

Byte

Unsigned 8-bit value.

Short

Signed 16-bit value.

UShort

Unsigned 16-bit value.

Long

Signed 32-bit value.

ULong

Unsigned 32-bit value.

Indx

Signed value, same size as a pointer on the system in use.

ULongLong

Unsigned 64-bit value.

LongLong

Signed 64-bit value.

Float

IEEE 754 single-precision real floating-point value.

Double

IEEE 754 double-precision real value.

LDouble

A C99 "long double", defined as "at least as precise as a double", but often more precise.

CFloat

A C99 complex single-precision floating-point value.

CDouble

A C99 complex double-precision floating-point value.

CLDouble

A C99 complex "long double" - see above for description.

PDL::Type OBJECTS

This module declares one class - PDL::Type - objects of this class are returned by the type method of an ndarray. It has several methods, listed below, which provide an easy way to access type information:

Additionally, comparison and stringification are overloaded so that you can compare and print type objects, e.g.

$nofloat = 1 if $pdl->type < float;
die "must be double" if $type != double;

For further examples check again the type method.

enum

Returns the number representing this datatype (see get_datatype).

symbol

Returns one of 'PDL_SB', 'PDL_B', 'PDL_S', 'PDL_US', 'PDL_L', 'PDL_UL', 'PDL_IND', 'PDL_ULL', 'PDL_LL', 'PDL_F', 'PDL_D', 'PDL_LD', 'PDL_CF', 'PDL_CD', or 'PDL_CLD'.

ctype

Returns the macro used to represent this type in C code (eg 'PDL_Long').

convertfunc

Synonym for ctype.

ppsym

The letter used to represent this type in PP code (eg 'U' for ushort).

realctype

The actual C type used to store this type.

shortctype

The value returned by ctype without the 'PDL_' prefix.

badvalue

The special numerical value used to represent bad values for this type. See "badvalue" in PDL::Bad for more details.

isnan

Given a string representing a C value, will return a C expression for this type that indicates whether that value is NaN (for complex values, if either is NaN).

isfinite

Given a string representing a C value, will return a C expression for this type that indicates whether that value is finite (for complex values, if both are finite).

floatsuffix

The string appended to floating-point functions for this floating-point type. Dies if called on non-floating-point type.

orig_badvalue

The default special numerical value used to represent bad values for this type. (You can change the value that represents bad values for each type during runtime.) See the orig_badvalue routine in PDL::Bad for more details.

bswap

Returns the appropriate bswap* from PDL::IO::Misc for the size of this type, including a no-op for types of size 1. Note this means a one-line construction means you must call the return value:

$pdl->type->bswap->($pdl);

real

Returns whether the type is real-only (true) or can hold complex values (false).

die "Real data only!" if !$pdl->type->real;

unsigned

Returns whether the type can hold signed values (false) or not (true).

integer

Returns whether the type can hold non-integer, a.k.a. floating-point, values (false) or not (true).

DEVELOPER NOTES ON ADDING/REMOVING TYPES

You can change the types that PDL knows about by editing entries in the definition of the variable @types that appears close to the top of the file Types.pm.PL (i.e. the file from which this module was generated).

Format of a type entry

Each entry in the @types array is a hash reference. Here is an example taken from the actual code that defines the ushort type:

{
 identifier => 'US',
 onecharident => 'U',   # only needed if different from identifier
 pdlctype => 'PDL_Ushort',
 realctype => 'unsigned short',
 ppforcetype => 'ushort',
 usenan => 0,
 packtype => 'S*',
 defaultbadval => 'USHRT_MAX',
 real=>1,
 integer=>1,
 unsigned=>1,
},

Before we start to explain the fields please take this important message on board: entries must be listed in order of increasing complexity. This is critical to ensure that PDL's type conversion works correctly. Basically, a less complex type will be converted to a more complex type as required.

Fields in a type entry

Each type entry has a number of required and optional entry.

A list of all the entries:

• identifier

  Required. A short sequence of uppercase letters that identifies this type uniquely. More than three characters is probably overkill.

• onecharident

  Optional. Only required if the identifier has more than one character. This should be a unique uppercase character that will be used to reference this type in PP macro expressions of the TBSULFD type - see "$T" in PDL::PP.

• pdlctype

  Required. The typedefed name that will be used to access this type from C code.

• realctype

  Required. The C compiler type that is used to implement this type. For portability reasons this one might be platform dependent.

• ppforcetype

  Required. The type name used in PP signatures to refer to this type.

• usenan

  Required. Flag that signals if this type has to deal with NaN issues. Generally only required for floating point types.

• packtype

  Required. The Perl pack type used to pack Perl values into the machine representation for this type. For details see perldoc -f pack.

• integer

  Required. Boolean - is this an integer type?

• unsigned

  Required. Boolean - is this an unsigned type?

• real

  Required. Boolean - is this a real (not complex) type?

• realversion

  String - the real version of this type (e.g. cdouble -> 'D').

• complexversion

  String - the complex version of this type (e.g. double -> 'C').

Also have a look at the entries at the top of Types.pm.PL.

The syntax is not written into stone yet and might change as the concept matures.

Other things you need to do

You need to check modules that do I/O (generally in the IO part of the directory tree). In the future we might add fields to type entries to automate this. This requires changes to those IO modules first though.

You should also make sure that any type macros in PP files (i.e. $TBSULFD...) are updated to reflect the new type. PDL::PP::Dump has a mode to check for type macros requiring updating. Do something like

find . -name \*.pd -exec perl -Mblib=. -M'PDL::PP::Dump=typecheck' {} \;

from the PDL root directory after updating Types.pm.PL to check for such places.

cpanm PDL

perl -MCPAN -e shell
install PDL