The BCH formula and the symmetric BCH formula up to terms of degree 20
by Fernando Casas and Ander Murua
The BCH formula written in a basis of the free Lie algebra
log(exp(X) exp(Y)) = X + Y + 1/2 [X,Y] + 1/12 [X,[X,Y]] - 1/12 [Y,[X,Y]] - 1/24[Y,[X,[X,Y]]] + ...
The symmetric BCH formula written in a basis of the free Lie algebra
log(exp(X/2) exp(Y) exp(X/2)) = X + Y - 1/24 [X,[X,Y]] - 1/12 [Y,[X,Y]] + ...
Back