Discrete dipole approximation codes. This is a list of Discrete Dipole Approximation (DDA) codes. The "code" here indicates computer code, a particular implementation of the DDA (many of them are open-source). For theoretical approach see Discrete dipole approximation article.
Most of the codes apply to arbitrary-shaped inhomogeneous nonmagnetic particles and particle systems in free space or homogeneous dielectric host medium. The calculated quantities typically include the Mueller matrices, integral cross-sections (extinction, absorption, and scattering), internal fields and angle-resolved scattered fields (phase function). There are some published comparisons of existing DDA codes.
These codes typically use regular grids (cubical or rectangular cuboid), conjugate gradient method to solve large systems of linear equations, and FFT-acceleration of the matrix-vector products which uses convolution theorem. Complexity of this approach is almost linear in number of dipoles for both time and memory.
These list include codes that do not qualify for the previous section. The reasons may include the following: source code is not available, FFT acceleration is absent or reduced, the code focuses on specific applications not allowing easy calculation of standard scattering quantities.