Dear developeRs, The topic has been raised quite a few times in r-devel and r-help before: calculation of matrix exponentials in R. We needed it in the actuar package at the C level and ended up cooking up our own solution based on expm() of package Matrix (which is itself based on Octave's). If there is interest from the R Core Team, we (my colleague in CC and I) are offering to contribute an expm() function to base R, with the corresponding C function part of the R API for package authors to use. We feel this would be a welcome addition to base R. Please share your thoughts. Best, --- Vincent Goulet, Associate Professor ?cole d'actuariat Universit? Laval, Qu?bec Vincent.Goulet at act.ulaval.ca http://vgoulet.act.ulaval.ca