ADMM

Implements the Alternating Direction Method of Multipliers (ADMM) and Three-Weight Algorithm (TWA).

See example applications (Sudoku and Circle Packing), but basic library usage:

1. Create an ObjectiveGraph.
2. Use the createVariable method to instantiate variables with initial values/weights.
3. Use the createFactor method to create factors that minimize local sub-objectives; edges (via createEdge) provide input/output access to existing variables.
4. Use the iterate method to perform one step of minimization on the left, followed by variable-value concur on the right; the iterations and converged properties provide status.

Between iterations...

• Subscripts can be used to get the value variables, as well as enable/disable factors.
• The reinitialize method resets the graph to its initial state (initial values/weights, all factors enabled).

Supplied example of "fast" circle packing shows integration with a spatial index for dynamic graph management, as well as use of callbacks (functions called after iteration/reinitialization).

The supplied example.swift is an example external client program:

• make (compiles the ADMM library and example program to an example folder)
• make run (run the example program, which is a shortcut for handling dynamic linking)
• make test (run all the tests in the package)
• make clean (delete the example/testing intermediate files/folders)