To cite package ‘expm’ in publications use:

Maechler M, Dutang C, Goulet V (2026). expm: Matrix Exponential, Log, 'etc'. R package version 1.0-1, https://CRAN.R-project.org/package=expm.

Corresponding BibTeX entry:

  @Manual{,
    title = {expm: Matrix Exponential, Log, 'etc'},
    author = {Martin Maechler and Christophe Dutang and Vincent
      Goulet},
    year = {2026},
    note = {R package version 1.0-1},
    url = {https://CRAN.R-project.org/package=expm},
  }