GDL is a free/libre/open source incremental compiler compatible with IDL (Interactive Data Language) and to some extent with PV-WAVE. Together with its library routines it serves as a tool for data analysis and visualization in such disciplines as astronomy, geosciences and medical imaging. GDL development had been started by Marc Schellens back in early noughties and has since continued with help of a team of maintainers, developers, packagers and thanks to feedback from users.
IDL is a registered trademark of Harris Geospatial Solutions. PV-WAVE is a product of Rogue Wave Software.