Mathematics tools already packaged in Debian
Computer Algebra Systems
See DebianScience/ComputerAlgebraSystems for a comparison of some of these.
Categories from http://axiom-wiki.newsynthesis.org/RosettaStone
yacas Computer Algebra System. Yacas is a small and highly flexible computer algebra language. The syntax is very close to Mathematica. The distribution contains a small library of mathematical functions, but its real strength is in the language in which you can easily write your own symbolic manipulation algorithms. It supports arbitrary precision arithmetic.
gap Groups, Algorithms and Programming computer algebra system
magnus Computational group theory software with GUI
aribas Interpreter for big integer and multiprecision floats arithmetic
pari-gp PARI/GP Computer Algebra System binaries
ginac-tools Some tools for the GiNaC symbolic framework. GiNaC (which stands for "GiNaC is Not a CAS (Computer Algebra System)") is a library for doing symbolic (i.e. non-numeric) computation directly in the C++ programming language.
libmatheval1 GNU library for evaluating symbolic mathematical expressions
Numerical computation oriented
freemat mathematics framework (mostly matlab compatible)
coq proof assistant for higher-order logic
geomview interactive geometry viewing program
atlas (Andre Lehovich)
lapack (Andre Lehovich)
Mathematics tools that could be considered for inclusion in Debian
matpack (Victor Munoz)
Mathematics tools that cannot go to main for licensing reasons
SCILAB (Rick Bahague)