Another issue surfaced in the meantime that I had to address, regarding how to treat results of match that ended with the retirement of one of the players. My aim with this ranking is to take into account only what is really played (which IMO is in the spirit of the Elo rating system), and my atomic unit is a set, so if a player retired without completing a set, in my system I will award that set to his opponent, regardless of what was the result in that set at the moment of retirement.
Today Stepanek retired against Benneteau at 0-0, 15/40, so, for the purpose of Elo rating I will record this match as 1-0 for Benneteau.
Yesterday G. Zemlja retired against A. Falla at 6-4, 3-1 for Falla, so this match is recorded as 2-0 for Falla.
And, if for example a player won the first set, and then retired in the second, I will record this match as 1-1.
You get the picture...