Editing Perl Data Language (section)

==Language design==
PDL is a vectorized [[array programming]] language: the expression syntax is a variation on standard mathematical [[Vector (geometric)|vector]] notation, so that the user can combine and operate on large arrays with simple expressions. In this respect, PDL follows in the footsteps of the [[APL programming language]], and it has been compared to commercial languages such as [[MATLAB]] and [[Interactive Data Language]], and to other free languages such as [[NumPy]] and [[GNU Octave#Octave.2C the language|Octave]].<ref>{{Cite web|url=http://blogs.perl.org/users/lhermida/2011/03/hi-everyone-as-a-bioinformatician.html|title=Putting Perl Back on Top in the Fields of Scientific and Financial Computing}}</ref> Unlike MATLAB and IDL, PDL allows great flexibility in indexing and vectorization: for example, if a subroutine normally operates on a 2-D [[matrix (mathematics)|matrix]] array, passing it a 3-D [[data cube]] will generally cause the same operation to happen to each 2-D layer of the cube.<ref>{{Cite web|url=http://pdl.perl.org/?docs=Threading&title=PDL::Threading|title=PDL online documentation (PDL::Threading section)}}</ref>

PDL borrows from Perl at least three basic types of program structure: [[imperative programming]], [[functional programming]], and [[pipeline programming]] forms may be combined. Subroutines may be loaded either via a built-in [[autoload]] mechanism or via the usual Perl module mechanism.