This updates the WDL model based on the LTC statistics for the last month (8M games).
for old results see:
https://github.com/official-stockfish/Stockfish/pull/3582
https://github.com/official-stockfish/Stockfish/pull/2778
the model changed a bit from the past, some images to follow in the PR
closes https://github.com/official-stockfish/Stockfish/pull/3981
No functional change.
// Coefficients of a 3rd order polynomial fit based on fishtest data
// for two parameters needed to transform eval to the argument of a
// logistic function.
// Coefficients of a 3rd order polynomial fit based on fishtest data
// for two parameters needed to transform eval to the argument of a
// logistic function.
- double as[] = {-3.68389304, 30.07065921, -60.52878723, 149.53378557};
- double bs[] = {-2.0181857, 15.85685038, -29.83452023, 47.59078827};
+ double as[] = {-1.17202460e-01, 5.94729104e-01, 1.12065546e+01, 1.22606222e+02};
+ double bs[] = {-1.79066759, 11.30759193, -17.43677612, 36.47147479};
double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];
double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];
double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];
double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];