3 papers
math-ph2020
A note on the Baker--Campbell--Hausdorff series in terms of right-nested commutators
Ana Arnal, Fernando Casas, Cristina Chiralt
We get compact expressions for the Baker--Campbell--Hausdorff series $Z = \log(\e^X \, \e^Y)$ in terms of right-nested commutators. The reduction in the number of terms originates…
math-ph2017
A general formula for the Magnus expansion in terms of iterated integrals of right-nested commutators
Ana Arnal, Fernando Casas, Cristina Chiralt
We present a general expression for any term of the Magnus series as an iterated integral of a linear combination of independent right-nested commutators with given coefficients. T…
math-ph2017
A note on trigonometric identities involving non-commuting matrices
Ana Arnal, Fernando Casas, Cristina Chiralt
An algorithm is presented for generating successive approximations to trigonometric functions of sums of non-commuting matrices. The resulting expressions involve nested commutator…