As you can see, Codeforces doesn't provide real rating, and we can only use the length of rating changes to calculate the real rating. The official blog wrote that CF rating calculator uses real rating to calculate rating changes, that is, we should get all people's real ratings to predict the rating changes. But method user.rating of Codeforces API can only get ONE account's rating changes in one attempt, so it's quite hard to do it. Hope Codeforces API can add realRating into User object :)
What do you mean by real rating?
I think he means the seed value which is needed to calculate rating changes.
Almost there. Codeforces said:
The rating of the new account will be equal to 0 for display (but it will be equal to 1400 when calculating rating changes).
So we cannot use current rating to calculate predicted rating changes.
It seems that this feature has been delayed for a loooooong time. :(
Hope it can be fixed quickly so that CF Predictor can work as usual.
MikeMirzayanov Please!