This is natural logarithm (base e). So ln 2 ~ 0.69, i.e. 69 elo for a speed doubling.
This is for engines playing orthodox chess, and seems to be quite universal. (Except when the level of play gets so high that almost all games end in a draw; then doubling the speed doesn't give so much Elo gain anymore, because even a perfect player can only beat a weaker player when the latter makes an error.)
This is natural logarithm (base e). So ln 2 ~ 0.69, i.e. 69 elo for a speed doubling.
This is for engines playing orthodox chess, and seems to be quite universal. (Except when the level of play gets so high that almost all games end in a draw; then doubling the speed doesn't give so much Elo gain anymore, because even a perfect player can only beat a weaker player when the latter makes an error.)