Versions of spam prior to 1.00 included a LICENSE file that described the license of some Fortran routines incompatible with the general R philosophy. The routines are in src/cholmodified.f. For the packages SparseM and spam, Esmond Ng and Barry Peyton have very kindly given permission to use their routines under an open source license (2012/03/09 and 2014/08/29). They have requested that their code be credited via the following two publications:

Esmond G. Ng and Barry W. Peyton, “Block sparse Cholesky algorithms on advanced uniprocessor computers”. SIAM J. Sci. Stat. Comput. 14 (1993), pp. 1034-1056.

John R. Gilbert, Esmond G. Ng, and Barry W. Peyton, “An efficient algorithm to compute row and column counts for sparse Cholesky factorization”. SIAM J. Matrix Anal. Appl. 15 (1994), pp. 1075-1091.

The old license file of spam versions <1.0 is in ./inst/0LICENCE