The biggest development this week was working out what is needed to get the coupled_spin which implements spin coupling merged back into master. There were some things to clean up with non-spin modules and a few minor things to address, but in cleaning this up, there will be some big changes to the way spin coupling works. First, with respect to things that have been implemented, rewrite and represent will no longer handle the coupling and uncoupling of states. To do coupling and uncoupling, instead, a couple and uncouple method will be created to handle the coupling and uncoupling of states. In addition, coupled states will now be represented by new classes, J?KetCoupled for the Cartesian directions. These will be returned by rewrite when a TensorProduct is coupled and will return the proper vector for the coupled space when it is represented and can be uncoupled when an uncoupled operator acts on it.

Most of these new changes have been implemented to varying degrees. There is some functionality lacking, but much of what remains for this is to implement tests for the new functions and make sure everything is working properly.

The coupling of arbitrary number of spin spaces had made slow progress due to some ambiguity when coupled states were created using normal states, but with the new Coupled classes, specifying the coupling should be possible, thus making the computations easier.