IDL uses different online help systems on UNIX and Windows platforms; the differences are described in detail below. All versions of IDL include the complete IDL documentation set in Adobe Portable Document Format (PDF).
The complete IDL documentation set is available in a set of Adobe Portable Document Format (PDF) files. Adobe Systems Inc. created the Portable Document Format in the early 1990s, basing it on their PostScript language. PDF is intended to allow documents to be displayed in exactly the same manner on a wide variety of computing platforms.
The IDL PDF files are electronic representations of the individual books in the documentation set, and can be either viewed on screen or printed (in full or in part) on a local printer. When viewed on-screen, the PDF books provide hyperlinked cross-references, tables of contents, and indices, allowing for speedy navigation through the set. In addition, some versions of the Adobe Acrobat software provide a fast full-text search capability, using a pre-compiled full-text index of the entire document set.
Viewing PDF files requires a separate application, not included in the IDL installation. Various versions of the Adobe Acrobat application are in wide use, and may already be installed on your system. The Adobe Acrobat Reader application is available free of charge from Adobe at
http://www.adobe.com. In addition, the most current version of Acrobat Reader available for each platform supported by IDL at the time of IDL's release is included on the IDL CD-ROM.
?command and ONLINE_HELP procedure to work. See UNIX Online Help for details.
The PDF version of the documentation set is available on all platforms, in the
Help subdirectory of the IDL distribution.
On Microsoft Windows systems, IDL uses the Windows native HTML Help system to display context-sensitive help and most documentation for IDL language features and routines. In addition, the HTML Help files in the IDL online help system contain hypertext links to the full IDL documentation set in PDF format.
On UNIX systems, IDL's online help system launches a copy of the Adobe Acrobat software to display help information. As a result, using IDL's online help system on a UNIX system requires that a version of Adobe Acrobat be installed on the system, and that the corresponding
acroread command be available in a directory included in your UNIX
PATH environment variable. See the Installing and Licensing IDL manual for details on installing and configuring Acrobat for use with IDL.
In addition, on most UNIX platforms, IDL uses an Adobe Acrobat plug-in that handles communication between IDL and Acrobat. The plug-in allows you to control some Acrobat functions from within IDL, most notably specifying a search term along with the IDL
? command - see IDL's Acrobat Plug-In below for details.
On platforms where the IDL Acrobat plug-in is not available, the
? command (with or without a search term) will cause IDL to launch Acrobat and open the PDF documentation set to a default page. You can then use the navigation facilities of the PDF documents and Acrobat itself to locate the appropriate topic.
The IDL Acrobat plug-in is a piece of software provided by RSI that handles communication between IDL and the version of Acrobat installed on the system. On platforms that support the plug-in, it is installed along with IDL and launched automatically when you use either the
? command or the ONLINE_HELP procedure. The plug-in provides the following features:
?command or ONLINE_HELP procedure. If the specified topic exists, it will be displayed in Acrobat. If the topic does not exist, a default topic is displayed instead.
For example, specifying
at the IDL command line on a UNIX system that supports the plug-in will cause Acrobat to display the entry for the FFT function from the IDL Reference Guide.
?command or the ONLINE_HELP procedure).
For a variety of reasons, some IDL platforms do not support the IDL Acrobat plug-in. On these platforms, IDL will launch a copy of Acrobat if one is available, optionally passing the name of a PDF file for Acrobat to open. IDL has no avenue of communication with the Acrobat process after it has been launched, however, and none of the above-listed features are available. For example, specifying
at the IDL command line on a UNIX system that does not support the plug-in will cause IDL to display an error message and Acrobat to display the first page of the IDL Reference Guide.
?command or the ONLINE_HELP procedure. Under Microsoft Windows, Acrobat is only launched if the ONLINE_HELP procedure is called with the name of a PDF file as the value of the BOOK keyword.
As of IDL 6.1, the IDL Acrobat plug-in is not available for the following platforms:
For additional information on the IDL Acrobat plug-in, see the
idl_acrobat_plugin.README file located in the
help subdirectory of the IDL distribution.