Space Missions: Long term preservation of IDL-based softwares using GDL

Alain Coulais (LERMA, CNRS and Paris Observatory), Sylwester Arabas (Faculty of Physics, University of Warsaw, Poland)


GNU Data Language (GDL) is an Open Source clone of IDL (ITTVIS
[link]), a interactive language widely used in Astronomy and Space
missions since decades. Proprietary language, licensing, price,
perennity, platforms choice of IDL are a concern in Astronomy
community since a long time, especially in Space Missions, where long
term supports are mandatory.

GDL is under GNU GPL v2/v3 license. All the key dependences of GDL are
on GPL or BSD licenses and are mainstream libraries, which shall give
guaranty of long term support: Plplot [link], ImageMagick [link], GSL

The GDL interpreter has full compatibility with IDL 7.1 and includes
support for selected features introduced in IDL 8 (negative indexes
...). Except on the Widget side, GDL has reached a state where it
becomes a viable alternative to IDL. It can be use to run large
pipelines based on codes and libraries written in IDL syntax, reading
back data, doing complex computations and delivering accurate results.

Refereed papers in various fields (Solar Physics, Data processing,
Cosmology, ...) are based on computations done with GDL, using well
known libraries written in IDL syntax (AstroLib [link], HealPix [link,
ref], MPfit [link, ref], ...), reading same input data files
(e.g. FITS files) and giving same results than IDL.

Not only widely used libraries are, in large proportion, working with
GDL, but also several formats, including FITS [ref, link, note], XDR
[link, note], PDS [link], and limited cases in HDF and NetCDF.

Thanks to many packagers, GDL is regularly packaged for most main
Linux distributions (Debian, Ubuntu, Fedora, Arch, ...), BDS and also
for OSX. Large test suite helps to avoid any regressions, asset
reliability for computations and assure safer deployments on new
systems, where customization may be required.

GDL is open to contributors, welcome feedback from the community to
catch last bugs, to extend missing functionalities and keywords
supports, and to ensure compatibilities with IDL-based libraries.

As a result GDL reached the level of ''commodity'' ensuring long term
preservation of analysis capabilities for the numerous ground
experiments and spaces missions which used or are still using IDL.

Slides in PDF format

Paper ID: O11

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