IDL TUTORIAL

This tutorial for the Interactive Data Language (IDL) was developed for graduate students in an introductory course on astronomical techniques at the University of Virginia. It consists of a guide to the basic functions of IDL and a set of exercises, both oriented toward 2-dimensional image processing:

• My Guide to IDL for Astronomers provides background information on IDL and an overview of many of the commands used in the exercises.

• The exercises illustrate the interactive computational environment of IDL and cover some of the basic IDL commands, utilities, and procedures, including: the use of scalars, vectors, and arrays; plotting; making graphics hardcopies; data I/O; 2-D image displays; and simple image processing and photometry techniques. Sample data sets are provided.
  The tutorial is intended to be self-guiding. It is not specific to the UVa IDL installation. Although the data sets are mostly astronomical, the exercises should be useful to the general audience of potential IDL users. With one exception, answers to the exercises are not provided, but simple trial and error should quickly reveal the correct methods.

Using the exercises

You will need a reference list of standard IDL commands to consult as you go through the exercises. Most convenient is the printed "IDL HandiGuide" (click here for the v5.4 version). Most thorough is the "IDL Reference Guide" (printed or PDF version). Available during any IDL session is the IDL HyperHelp system, which you invoke by typing ? as the first element of a line.
All of these exercises could be completed using intrinsic IDL routines and the Exelis-supplied User's Library. However, in some instances the built-ins can be awkward, and I have assumed you have access to routines from the IDL Astronomy User's Library (AstUseLib) and the MOUSSE routines from the UIT project. These are pre-installed on the UVa Astronomy Department server.
Other users can obtain a gzipped UNIX tar file of the Astronomy User's Library from the AstUseLib Homepage.
Selected MOUSSE routines are available individually or in the form of a tar file in the minimousse directory.
To execute the MOUSSE routines, you will also need a special "startup" file named mousse_startup.pro, which will be executed at the beginning of your IDL session if you point the UNIX environment variable $IDL_STARTUP to it.
In order to access any such external software during your IDL session, all you need to do is to place the individual *.pro program files in your IDL path. The programs will be automatically compiled when you request them.

Other tips

• Help on any intrinsic IDL routine is available through your browser during an IDL session if you type ?[name].

• Remember that the source code for any IDL program except the RSI intrinsic routines is available for you to inspect at any time. To compile a program and simultaneously list it to your terminal, type .run -t [name].

• To see only the informational header of non-intrinsic routines, use the MOUSSE command man,'[name].

• Most non-intrinsic routines are coded such that if you simply type the name of the routine without parameters, it will return a list of the expected parameters.

• For parameter lists of intrinsic routines, give the help,/rou command.

• Further information on getting help is available in the Guide to IDL.

• In the exercises, most commands are given in CAPITAL letters, so they will stand out, but since IDL is case-insensitive, you needn't follow this convention (except for file names).

The exercises were developed for Unix/Linux/MAC OS-X workstations. Most should work well in Microsoft Windows, though there may be occasional hangups with displays and such.

Please let me know of errors or difficulties you encounter with the tutorial.

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Tutorial:

• IDL Exercises I (scalars, vectors, plotting)

• IDL Exercises II (arrays and image displays)

• IDL Exercises III (image processing)

  
  

• Test data sets and miscellaneous software

• Selected MOUSSE software for exercises

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Useful Links:

• Index to general IDL resources

• Guide to IDL for Astronomers

• IDL Astronomy User's Library (GSFC)

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Translations of this page:

• Danish translation

• Polish translation

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Last modified December 2020 by Robert W. O'Connell

All contents of this Tutorial are copyright © 2000-2020 by Robert W. O'Connell.
All rights reserved.

Source URL:
https://rwoconne.github.io/rwoclass/astr511/IDLexercises/index.html