The latest version of the DanIDL library is v3.0. It contains 278 individual modules, each with full documentation and specifications on input/output. Certain modules have the option of using C++ versions of the code, also supplied within the library, in order to speed up the heaviest parts of the calculations. The IDL (and C++) code is highly optimised for speed and reliability.

If DanIDL modules are used for any work that is to be published, then I would appreciate the addition of the following sentence in the acknowledgements: "This research has made use of the DanIDL library of routines (http://www.danidl.co.uk)". Also, DanIDL is listed in the Astrophysics Source Code Library (ASCL), which may be useful for providing an appropriate reference or citation, e.g. Bramich D. M., <Year>, DanIDL v3.0, Astrophysics Source Code Library, record ascl:1709.005.

Modules and functions in v3.0 of DanIDL are organised into the following broad subject areas:

• Array.Manipulation
• Astrometry
• Bad.Pixel.Mask.Processing
• Checks.And.Tests
• Constants
• Conversions
• Convolution
• Data.Cube.Processing.General
• Data.Manipulation
• Filename.Operations
• Functions.General
• Geometry
• Image.Processing.General
• Math
• Matrices
• Polynomials
• Sequences.And.Series
• Set.Operations
• Spherical.Geometry
• Statistics
• String.Operations
• Text.File.Operations
• Times.And.Dates
• Variables.Management
• Variance.Propagation
• Vector.Processing.General