An interesting (later) paper about generating the Stern-Brocot tree and the Calkin-Wilf tree simultaneously from a sequence of 2x2 matrices: http://www.cs.nott.

An interesting (later) paper about generating the Stern-Brocot tree and the Calkin-Wilf tree simultaneously from a sequence of 2x2 matrices: http://www.cs.nott.ac.uk/~psarb2/MPC/RecountingRationalsTwice.pdf http://www.cs.nott.ac.uk/~psarb2/MPC/RecountingRationalsTwic...