1COURSE(1) User Contributed Perl Documentation COURSE(1)
2
6 PDL::Course - A journey through PDL's documentation, from beginner to
7 advanced.
8
10 This is written by David Mertens with edits by Daniel Carrera.
11
13 PDL's documentation is extensive. Some sections cover deep core magic
14 while others cover more usual topics like IO and numerical computation.
15 How are these related? Where should you begin?
16 This document is an attempt to pull all the key PDL documentation
18 together in a coherent study course, starting from the beginner level,
19 up to the expert.
20 I've broken down everything by level of expertise, and within expertise
22 I've covered documentation, library, and workflow modules. The
23 documentation modules are useful for what they tell you; the library
24 modules are useful for the functions that they define for you; the
25 workflow modules are useful for the way that they allow you to get your
26 work done in new and different ways.
27
29 If you are new to PDL, these documentation modules will get you started
30 down the right path for using PDL.
31 Documentation
33 Modules that tell you how to start using PDL. Many of these are
34 library modules technically, but they are included when you "use PDL",
35 so I've included them for their documentation.
36 After the first three, most of the docs listed below are rather dry.
38 Perhaps they would be better summarized by tables or better synopses.
39 You should at least scan through them to familiarize yourself with the
40 basic capabilities of PDL.
41 • PDL::Philosophy, PDL::QuickStart
43 A couple of brief introductions to PDL. The second one is a bit
45 more hands-on. If you are new to PDL, you should start with these.
46 • PDL::Basic
48 Covers basic ndarray-creation routines like "sequence", "rvals",
50 and "logxvals" to name a random few. Also covers "hist" and
51 "transpose".
52 • PDL::Ufunc
54 Explains a large collection of built-in functions which, given an
56 N-dimension ndarray, will create an ndarray with N-1 dimensions.
57 • PDL::NiceSlice
59 PDL came of age right around the turn of the millennium and
61 NiceSlice came on the scene slightly after that. Some of the docs
62 still haven't caught up. NiceSlice is the 'modern' way to slice
63 and dice your ndarrays. Read the Synopsis, then scroll down to The
64 New Slicing Syntax. After you've read to the bottom, return to and
65 read the stuff at the top.
66 • PDL::Primitive
68 Defines a whole slew of useful built-in functions. These are the
70 sorts of things that beginners are likely to write to the list and
71 say, "How do I do xxx?" You would be well on your way to learning
72 the ropes after you've gotten through this document.
73 • Selections from PDL::Core
75 Like PDL::Primitive, defines a large set of useful functions.
77 Unfortunately, some of the functions are quite esoteric, but are
78 mixed in with the rest of the simple and easy ones. Skim the whole
79 document, skipping over the complicated functions for now. I would
80 point out in particular the function "approx".
81 Workflow
83 • The perldl or pdl2 Shell
84 The Perldl Shell is a REPL (Read-Evaluate-Print-Loop, in other
86 words, a prompt or shell) that allows you to work with PDL (or any
87 Perl, for that matter) in 'real time', loading data from files,
88 plotting, manipulating... Anything you can do in a script, you can
89 do in the PDL Shell, with instant feedback!
90 Libraries
92 • PDL
93 The main workhorse module. You'll include this in nearly every PDL
95 program you write.
96
98 The sorts of modules that you'll likely use on a normal basis in
99 scripts or from within the perldl shell. Some of these modules you may
100 never use, but you should still be aware that they exist, just in case
101 you need their functionality.
102 Documentation
104 • PDL::Slices
105 In addition to explaining the original slicing and dicing functions
107 - for which you can usually use PDL::NiceSlice - this also covers
108 many dimension-handling functions such as "mv", "xchg", and
109 "reorder". This also thoroughly documents the "range" function,
110 which can be very powerful, and covers a number of internal
111 functions, which can probably be skipped.
112 • PDL::Indexing
114 This covers a lot of the deeper conceptual ground that you'll need
116 to grasp to really use PDL to its full potential. It gets more
117 complex as you go along, so don't be troubled if you find yourself
118 loosing interest half way through. However, reading this document
119 all the way through will bring you much closer to PDL
120 enlightenment.
121 • PDL::IO
123 PDL has quite a few IO modules, most of which are discussed in this
125 summary module.
126 • PDL::Tips
128 A collection of some of Tuomas's ideas for making good use of PDL.
130 • PDL::BadValues
132 Explains what bad values are and how and why they are implemented.
134 • Selections from Inline::Pdlpp
136 Although writing PDL::PP code is considered an Advanced topic, and
138 is covered in the next section, you should be aware that it is
139 possible (and surprisingly simple) to write PDL-aware code. You
140 needn't read the whole thing at this point, but to get some feel
141 for how it works, you should read everything up through the first
142 example. A copy of this documentation is contained in
143 PDL::PP-Inline.
144 • PDL::Objects
146 Explains how to subclass an ndarray object.
148 • PDL::Index
150 This was discussed in the Preface. It is an automatically generated
152 file that lists all of the PDL modules on your computer. There are
153 many modules that may be on your machine but which are not
154 documented here, such as bindings to the FFTW library, or GSL. Give
155 it a read!
156 Libraries
158 • PDL::FFT
159 PDL's own Fast Fourier Transform. If you have FFTW, then you
161 should probably make use of it; this is PDL's internal
162 implementation and should always be available.
163 • GSL
165 PDL does not have bindings for every sub-library in the GNU
167 Scientific Library, but it has quite a few. If you have GSL
168 installed on your machine then chances are decent that your PDL has
169 the GSL bindings. For a full list of the GSL bindings, check
170 PDL::Index.
171 • PDL::Func
173 A somewhat uniform interface to the different interpolation modules
175 in PDL.
176 • PDL::Bad
178 Includes some basic bad-value functionality, including functions to
180 query if an ndarray has bad values ("isbad") and functions to set
181 certain elements as bad ("setbadat" and "setbadif"). Among other
182 places, bad values are used in PDL::Graphics::PLplot's xyplot to
183 make a gap in a line plot.
184 • PDL::DiskCache
186 A cool module that allows you to tie a Perl array to a collection
188 of files on your disk, which will be loaded into and out of memory
189 as ndarrays. If you find yourself writing scripts to process many
190 data files, especially if that data processing is not necessarily
191 in sequential order, you should consider using PDL::DiskCache.
192 • PDL::Char
194 A PDL subclass that allows you to store and manipulate collections
196 of fixed-length character strings using PDL.
197 • PDL::Image2D
199 A whole collection of methods for manipulating images whose image
201 data are stored in an ndarray. These include methods for
202 convolutions (smoothing), polygon fills, scaling, rotation, and
203 warping, among others.
204 • PDL::ImageND
206 Contains a few functions that are conceptually related to image
208 processing, but which can be defined for higher-dimensional data.
209 For examples this module defines high-dimensional convolution and
210 interpolation, among others.
211 • PDL::ImageRGB
213 Defines some useful functions for working with RBG image data.
215 It's not very feature-full, but it may have something you need, and
216 if not, you can always add more!
217 • PDL::Transform
219 Creates the transform class, which allows you to create various
221 coordinate transforms. For example, if you data is a collection of
222 Cartesian coordinates, you could create a transform object to
223 convert them to Spherical-Polar coordinates (although many such
224 standard coordinate transformations are predefined for you, in this
225 case it's called "t_spherical").
226 • PDL::Opt::Simplex
228 This package states that it "implements the commonly used simplex
230 optimization algorithm." I'm going to assume that if you need this
231 algorithm then you already know what it is.
232 • PDL::Math
234 A collection of fairly standard math functions, like the inverse
236 trigonometric functions, hyperbolic functions and their inverses,
237 and others. This module is included in the standard call to "use
238 PDL", but not in the Lite versions.
239 • PDL::Matrix
241 Provides a few functions that use the standard mathematical Matrix
243 notation of row-column indexing rather than the PDL-standard
244 column-row. It appears that this module has not been heavily
245 tested with other modules, so although it should work with other
246 modules, don't be surprised if something breaks when you use it
247 (and feel free to offer any fixes that you may develop).
248 • PDL::MatrixOps
250 Provides many standard matrix operations for ndarrays, such as
252 computing eigenvalues, inverting square matrices, LU-decomposition,
253 and solving a system of linear equations. Though it is not built
254 on PDL::Matrix, it should generally work with that module. Also,
255 the methods provided by this module do not depend on external
256 libraries such as Slatec or GSL.
257 • PDL::Reduce
259 Implements an interface to all the functions that return ndarrays
261 with one less dimension (for example, "sumover"), such that they
262 can be called by supplying their name, as a string.
263 Workflow
265 • PDL::AutoLoader
266 Enables Matlab-style autoloading. When you call an unknown
268 function, instead of complaining and croaking, PDL will go hunt
269 around in the directories you specify in search of a like-named
270 file. Particularly useful when used with the Perldl Shell.
271 • PDL::Dbg
273 Declares the "px" function, which can be handy for debugging your
275 PDL scripts and/or perldl shell commands.
276 • PDL::Options
278 Suppose you define a powerful, versatile function. Chances are
280 good that you'll accept the arguments in the form of a hash or
281 hashref. Now you face the problem of processing that hashref.
282 PDL::Options assists you in writing code to process those options.
283 (You'd think Perl would have tons of these sorts of modules lying
284 around, but I couldn't find any.) Note this module does not depend
285 on PDL for its usage or installation.
286 • PDL::pdldoc
288 Ever fired-up the perldl shell just to look up the help for a
290 particular function? You can use "pdldoc" instead. This shell
291 script extracts information from the help index without needing to
292 start the perldl shell.
293
295 The sorts of modules and documentation that you'll use if you write
296 modules that use PDL, or if you work on PDL maintenance. These modules
297 can be difficult to use, but enable you to tackle some of your harder
298 problems.
299 • PDL::Lite, PDL::LiteF
301 Lite-weight replacements for "use PDL", from the standpoint of
303 namespace pollution and load time.
304 • Inline::Pdlpp
306 This was mentioned earlier. Before you begin reading about PDL::PP
308 (next), you should remind yourself about how to use this.
309 Inline::Pdlpp will help you experiment with PDL::PP without having
310 to go through the trouble of building a module and constructing
311 makefiles (but see PDL::pptemplate for help on that).
312 • PDL::PP
314 The PDL Pre-Processor, which vastly simplifies making you C or
316 Fortran code play with Perl and ndarrays. Most of PDL's basic
317 functionality is written using PDL::PP, so if you're thinking about
318 how you might integrate some numerical library written in C, look
319 no further.
320 • PDL::pptemplate
322 A script that automates the creation of modules that use PDL::PP,
324 which should make your life as a module author a bit simpler.
325 • PDL::CallExt
327 Allows you to call functions using external shared libraries. This
329 is an alternative to using PDL::PP. The major difference between
330 PDL::PP and PDL::CallExt is that the former will handle
331 broadcasting over implicit broadcast dimensions for you, whereas
332 PDL::CallExt simply calls an external function. PDL::PP is
333 generally the recommended way to interface your code with PDL, but
334 it wouldn't be Perl if there wasn't another way to do it.
335 • PDL::Config
337 Defines the %PDL::Config hash, which has lots of useful information
339 pertinent to your PDL build.
340 • PDL::Doc
342 Explanation of the PDL documentation conventions, and an interface
344 to the PDL Documentation parser. Following these guidelines when
345 writing documentation for PDL functions will ensure that your
346 wonderful documentation is accessible from the perldl shell and
347 from calls to "barf". (Did you notice that "barf" used your
348 documentation? Time to reread PDL::Core...)
349 • PDL::Exporter
351 A simple replacement for the standard Exporter module. The only
353 major difference is that the default imported modules are those
354 marked ':Func'.
355 • PDL::Types
357 Defines some useful functions for getting an ndarray's type, as
359 well as getting information about that type.
360
362 • PDL::Core::Dev
363 Provides some decently useful functions that are pretty much only
365 needed by the PDL Porters.
366 • PDL::API
368 Explains how to make an ndarray by hand, from Perl or your C source
370 code, using the PDL API.
371 • PDL::Internals
373 Explains the nitty-gritty of the PDL data structures. After
375 reading this (a few times :), you should be able to create an
376 ndarray completely from scratch (i.e. without using the PDL API).
377 Put a little differently, if you want to understand how PDL::PP
378 works, you'll need to read this.
379
381 Copyright 2010 David Mertens (dcmertens.perl@gmail.com). You can
382 distribute and/or modify this document under the same terms as the
383 current Perl license.
384 See: http://dev.perl.org/licenses/
386perl v5.38.0 2023-07-21 COURSE(1)