S(33, 31), S(33, 31), S(29, 31), S(20, 28) }};
// Pawn chain membership bonus by file
- const Score ChainMember[FILE_NB] = {
- S(11,-1), S(13,-1), S(13,-1), S(14,-1),
- S(14,-1), S(13,-1), S(13,-1), S(11,-1)
- };
+ const Score ChainMember[FILE_NB][RANK_NB] = {
+ { S(0, 0), S(14, 0), S(16, 4), S(18, 9), S(28, 28), S(52, 104), S(118, 236) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(30, 30), S(54, 108), S(120, 240) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(30, 30), S(54, 108), S(120, 240) },
+ { S(0, 0), S(17, 0), S(19, 6), S(22, 11), S(33, 33), S(59, 118), S(127, 254) },
+ { S(0, 0), S(17, 0), S(19, 6), S(22, 11), S(33, 33), S(59, 118), S(127, 254) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(30, 30), S(54, 108), S(120, 240) },
+ { S(0, 0), S(16, 0), S(18, 5), S(20, 10), S(30, 30), S(54, 108), S(120, 240) },
+ { S(0, 0), S(14, 0), S(16, 4), S(18, 9), S(28, 28), S(52, 104), S(118, 236) }};
// Candidate passed pawn bonus by rank
const Score CandidatePassed[RANK_NB] = {
value -= Backward[opposed][f];
if (chain)
- value += ChainMember[f] + CandidatePassed[relative_rank(Us, s)] / 2;
+ value += ChainMember[f][relative_rank(Us, s)];
if (candidate)
{