sympy/sympy — pull request #1007 by flacjacket (2012-01-22 00:11:13+00:00)
Title: Improved checking of spin states

Implements checks when creating new SpinState's and CoupledSpinState's to ensure the arguments give a valid state. This includes checking integer/half-integer arguments and j/m relationships for both coupled and normal states and checking that the coupling is valid for coupled states.

In addition, changes the pretty printing of coupled spin states to use subscripted characters.

Fixes Issue 2973 [1]

[1] http://code.google.com/p/sympy/issues/detail?id=2973