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Shell scripting vs Perl scripting
09-06-2010
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INTRO(1) User Contributed Perl Documentation INTRO(1) NAME
PDL::Intro - Introduction to the Perl Data Language Version 2.0 "Why is it that we entertain the belief that for every purpose odd numbers are the most effectual?" - Pliny the Elder. Karl Glazebrook [karlglazebrook@yahoo.com] DESCRIPTION
Perl is an extremely good and versatile scripting language, well suited to beginners and allows rapid prototyping. However until recently it did not support data structures which allowed it to do fast number crunching. However with the development of Perl v5, Perl acquired Objects. To put it simply users can define their own special data types, and write custom routines to manipulate them either in low level languages (C and Fortran) or in Perl itself. This has been fully exploited by the PDL developers. The "PDL" module is a complete Object-Oriented extension to Perl (although you don't have to know what an object is to use it) which allows large N-dimensional data sets, such as large images, spectra, time series, etc to be stored efficiently and manipulated en masse. For example with the PDL module we can write the perl code "$a=$b+$c", where $b and $c are large datasets (e.g. 2048x2048 images), and get the result in only a fraction of a second. PDL variables (or piddles as they have come to be known) support a wide range of fundamental data types - arrays can be bytes, short inte- gers (signed or unsigned), long integers, floats or double precision floats. And because of the Object-Oriented nature of PDL new cus- tomised datatypes can be derived from them. As well as the PDL modules, that can be used by normal perl programs, PerlDL comes with a command line perl shell, called perldl, which supports command line editing. In combination with the various PDL graphics modules this allows data to be easily played with and visu- alised. SYNOPSIS
This manual page provides a general introduction to the underlying philosophy of PDL. For an overview over the rest of the documentation see PDL::Index. As a beginner the following documents are particulary recommended: PDL::Impatient Quick summary - PDL for the impatient PDL::FAQ The Frequently Asked Questions list for PDL. PDL::Philosophy Why another matrix language? PDL::Indexing An introduction to using smart indices in PDL. PDL::NiceSlice The all important slicing of piddles. AUTHOR
Copyright (C) Karl Glazebrook (karlglazebrook@yahoo.com), Tuomas J. Lukka, (lukka@husc.harvard.edu) and Christian Soeller (c.soeller@auck- land.ac.nz) 1997-2002. Commercial reproduction of this documentation in a different format is forbidden without permission. perl v5.8.0 2002-03-18 INTRO(1)