Differences

This shows you the differences between two versions of the page.

--- chess:programming:database [2022/01/11 10:25] – peter
+++ chess:programming:database [2022/01/11 10:50] (current) – peter
@@ Line 6: / Line 6: @@
 |Move From|6|A1=0, H1=7, A8=56, H8=63|File=<file>-'A', rank=<rank>-'1'. Castle and Enpassant moves are assumed to be valid moves.|
 |Move To|6|A1=0, H1=7, A8=56, H8=63|File=<file>-'A', rank=<rank>-'1'. Castle and Enpassant moves are assumed to be valid moves.|
-|Promotion Type|3|000=unused, 001=Knight, 010=Bishop, 011=Rook, 100=Queen.|
+|Promotion Type|3|000-111|000=unused, 001=Knight, 010=Bishop, 011=Rook, 100=Queen.|
 |White Elo|11|0-2047|Actual elo of white – 1000.|
 |Elo Diff|8|0-255|0-255=w, 256-511=b.|
 |Elo Diff Neg|1|0-1|0=positive, 1=negative.|
-|%WDL|9|0-511|0-99=W, 100-199=D, 200-299=L  Unused Values 300-511.|
+|%WDL|9|0-511|0-99=Percentage Win, 100-199=Percentage Draw, 200-299=Percentage Loss. From White Perspective. Unused Values 300-511.|
 |Count|12|0-4095|Rolling.|
-|Weight-ELO|8|0-255|A measure for the likelihood of a win after that particular move has been made. default is to use elo changes.|
+|Weight|8|0-255|A measure for the likelihood of a win after that particular move has been made. 0-127=w, 128-255=b. Default is to use ELO changes to calculate this.|
+<WRAP info>
+**NOTE:**  A total of 64-bits.
+</WRAP>
 ----
@@ Line 78: / Line 84: @@
 Range is 0-255.
-Default is to use elo changes.
+Default is to use ELO changes per this formula:
 <code>
-  P1 = (1.0 / (1.0 + std::pow(10.0, ((rating1 - rating2) / 400.0)) ) );
+  white_probability = (1.0 / (1.0 + std::pow(10.0, ((rating1 - rating2) / 400.0)) ) );
-  P2 = 1 - P1;
+  black_probability = 1 - white_probability;
+  if (rating1 > rating2)
+  {
+    result=-black_probability/20;
+  }
+  else
+  if (rating1 < rating2)
+  {
+    res=white_probability/20;
+  }
 </code>
+<WRAP info>
+**NOTE:**  A bespoke formula could be used to update this weighting.
+  * Instead of using the k factor/value of 400 that the original formula uses, this is changed to be 100 + ((score difference) * 2).
+  * So the max k factor would be 140 (20-0 is the biggest win, multiply by 2, add to 100).
+</WRAP>
 ----
 [[Chess:Programming:Database|Database]]