To cite fastmatrix in publications use:

Osorio F, Ogueda A (2021). Fast computation of some matrices useful in statistics. R package version 0.3-81, https://faosorios.github.io/fastmatrix/.

Corresponding BibTeX entry:

  @Manual{,
    title = {Fast computation of some matrices useful in statistics},
    author = {F. Osorio and A. Ogueda},
    year = {2021},
    note = {R package version 0.3-81},
    url = {https://faosorios.github.io/fastmatrix/},
  }