With the kind permission of the authors of Singular, G.-M. Greuel, R. Stobbe, G. Pfister, H. Schoenemann, and J. Schmidt, University of Kaiserslautern, Macaulay2 incorporates
Singular-Factory, version 4.2.1, a free library of polynomial routines that provides for factorization of polynomials. It is available at
ftp://www.mathematik.uni-kl.de/pub/Math/Singular/Factory and at
http://www.mathematik.uni-kl.de/ftp/pub/Math/Singular/SOURCES. It is part of
Singular, whose home page is
http://www.singular.uni-kl.de/.
The following important routines call upon it: