1Types(3) User Contributed Perl Documentation Types(3)
2
6 PDL::Types - define fundamental PDL Datatypes
7
9 use PDL::Types;
10 $pdl = ushort( 2.0, 3.0 );
12 print "The actual c type used to store ushort's is '" .
13 $pdl->type->realctype() . "'\n";
14 The actual c type used to store ushort's is 'unsigned short'
15
17 Internal module - holds all the PDL Type info. The type info can be
18 accessed easily using the "PDL::Type" object returned by the type
19 method as shown in the synopsis.
20 Skip to the end of this document to find out how to change the set of
22 types supported by PDL.
23
25 A number of functions are available for module writers to get/process
26 type information. These are used in various places (e.g. "PDL::PP",
27 "PDL::Core") to generate the appropriate type loops, etc.
28 typesrtkeys
30 Returns an array of keys of typehash sorted in order of type complexity
31 pdl> @typelist = PDL::Types::typesrtkeys;
33 pdl> print @typelist;
34 PDL_B PDL_S PDL_US PDL_L PDL_IND PDL_LL PDL_F PDL_D
35 ppdefs
37 Returns an array of pp symbols for all real types. This informs the
38 default "GenericTypes" for "pp_def" functions, making support for
39 complex types require an "opt-in".
40 pdl> print PDL::Types::ppdefs
42 B S U L N Q F D
43 ppdefs_complex
45 Returns an array of pp symbols for all complex types.
46 pdl> print PDL::Types::ppdefs_complex
48 G C
49 ppdefs_all
51 Returns an array of pp symbols for all types including complex.
52 pdl> print PDL::Types::ppdefs_all
54 B S U L N Q F D G C
55 typesynonyms
57 return type related synonym definitions to be included in pdl.h . This
58 routine must be updated to include new types as required. Mostly the
59 automatic updating should take care of the vital things.
60
62 As of 2.065, PDL supports these types:
63 SByte
65 Signed 8-bit value.
66 Byte
68 Unsigned 8-bit value.
69 Short
71 Signed 16-bit value.
72 UShort
74 Unsigned 16-bit value.
75 Long
77 Signed 32-bit value.
78 ULong
80 Unsigned 32-bit value.
81 Indx
83 Signed value, same size as a pointer on the system in use.
84 LongLong
86 Signed 64-bit value.
87 ULongLong
89 Unsigned 64-bit value.
90 Float
92 IEEE 754 <https://en.wikipedia.org/wiki/IEEE_754> single-precision
93 real floating-point value.
94 Double
96 IEEE 754 double-precision real value.
97 LDouble
99 A C99 "long double", defined as "at least as precise as a double",
100 but often more precise.
101 CFloat
103 A C99 complex single-precision floating-point value.
104 CDouble
106 A C99 complex double-precision floating-point value.
107 CLDouble
109 A C99 complex "long double" - see above for description.
110
112 This module declares one class - "PDL::Type" - objects of this class
113 are returned by the type method of an ndarray. It has several methods,
114 listed below, which provide an easy way to access type information:
115 Additionally, comparison and stringification are overloaded so that you
117 can compare and print type objects, e.g.
118 $nofloat = 1 if $pdl->type < float;
120 die "must be double" if $type != double;
121 For further examples check again the type method.
123 enum
125 Returns the number representing this datatype (see get_datatype).
126 symbol
128 Returns one of 'PDL_B', 'PDL_S', 'PDL_US', 'PDL_L', 'PDL_IND',
129 'PDL_LL', 'PDL_F' or 'PDL_D'.
130 ctype
132 Returns the macro used to represent this type in C code (eg
133 'PDL_Long').
134 convertfunc
136 Synonym for "ctype".
137 ppsym
139 The letter used to represent this type in PP code (eg 'U' for
140 ushort).
141 realctype
143 The actual C type used to store this type.
144 shortctype
146 The value returned by "ctype" without the 'PDL_' prefix.
147 badvalue
149 The special numerical value used to represent bad values for this
150 type. See "badvalue" in PDL::Bad for more details.
151 isnan
153 Given a string representing a C value, will return a C expression
154 for this type that indicates whether that value is NaN (for complex
155 values, if either is NaN).
156 isfinite
158 Given a string representing a C value, will return a C expression
159 for this type that indicates whether that value is finite (for
160 complex values, if both are finite).
161 floatsuffix
163 The string appended to floating-point functions for this floating-
164 point type. Dies if called on non-floating-point type.
165 orig_badvalue
167 The default special numerical value used to represent bad values
168 for this type. (You can change the value that represents bad values
169 for each type during runtime.) See the orig_badvalue routine in
170 PDL::Bad for more details.
171 bswap
173 Returns the appropriate "bswap*" from PDL::IO::Misc for the size of
174 this type, including a no-op for types of size 1. Note this means a
175 one-line construction means you must call the return value:
176 $pdl->type->bswap->($pdl);
178 real
180 Returns whether the type is real-only (true) or can hold complex
181 values (false).
182 die "Real data only!" if !$pdl->type->real;
184 unsigned
186 Returns whether the type can hold signed values (false) or not
187 (true).
188 integer
190 Returns whether the type can hold non-integer, a.k.a. floating-
191 point, values (false) or not (true).
192
194 You can change the types that PDL knows about by editing entries in the
195 definition of the variable @types that appears close to the top of the
196 file Types.pm.PL (i.e. the file from which this module was generated).
197 Format of a type entry
199 Each entry in the @types array is a hash reference. Here is an example
200 taken from the actual code that defines the "ushort" type:
201 {
203 identifier => 'US',
204 onecharident => 'U', # only needed if different from identifier
205 pdlctype => 'PDL_Ushort',
206 realctype => 'unsigned short',
207 ppforcetype => 'ushort',
208 usenan => 0,
209 packtype => 'S*',
210 defaultbadval => 'USHRT_MAX',
211 real=>1,
212 integer=>1,
213 unsigned=>1,
214 },
215 Before we start to explain the fields please take this important
217 message on board: entries must be listed in order of increasing
218 complexity. This is critical to ensure that PDL's type conversion works
219 correctly. Basically, a less complex type will be converted to a more
220 complex type as required.
221 Fields in a type entry
223 Each type entry has a number of required and optional entry.
224 A list of all the entries:
226 • identifier
228 Required. A short sequence of upercase letters that identifies this
230 type uniquely. More than three characters is probably overkill.
231 • onecharident
233 Optional. Only required if the "identifier" has more than one
235 character. This should be a unique uppercase character that will
236 be used to reference this type in PP macro expressions of the
237 "TBSULFD" type - see "$T" in PDL::PP.
238 • pdlctype
240 Required. The "typedef"ed name that will be used to access this
242 type from C code.
243 • realctype
245 Required. The C compiler type that is used to implement this type.
247 For portability reasons this one might be platform dependent.
248 • ppforcetype
250 Required. The type name used in PP signatures to refer to this
252 type.
253 • usenan
255 Required. Flag that signals if this type has to deal with NaN
257 issues. Generally only required for floating point types.
258 • packtype
260 Required. The Perl pack type used to pack Perl values into the
262 machine representation for this type. For details see "perldoc -f
263 pack".
264 • integer
266 Required. Boolean - is this an integer type?
268 • unsigned
270 Required. Boolean - is this an unsigned type?
272 • real
274 Required. Boolean - is this a real (not complex) type?
276 • realversion
278 String - the real version of this type (e.g. cdouble -> 'D').
280 • complexversion
282 String - the complex version of this type (e.g. double -> 'C').
284 Also have a look at the entries at the top of Types.pm.PL.
286 The syntax is not written into stone yet and might change as the
288 concept matures.
289 Other things you need to do
291 You need to check modules that do I/O (generally in the IO part of the
292 directory tree). In the future we might add fields to type entries to
293 automate this. This requires changes to those IO modules first though.
294 You should also make sure that any type macros in PP files (i.e.
296 "$TBSULFD...") are updated to reflect the new type. PDL::PP::Dump has a
297 mode to check for type macros requiring updating. Do something like
298 find . -name \*.pd -exec perl -Mblib=. -M'PDL::PP::Dump=typecheck' {} \;
300 from the PDL root directory after updating Types.pm.PL to check for
302 such places.
303perl v5.36.0 2023-01-20 Types(3)