Symbolic algebra

Explanation of tables
*green Function exists in octave 2.0.x
Noted incompatibilities and missing features
+yellow Function exists in matcompat
Author and home for the function.
?orange Function doesn't exist
Explanation of what you can do instead.
xred Function doesn't exist, and no work-around

Ben Sapp has some support for symbolic math available. As you can see from this list, there is much work to be done, so help him out.

Creation
?sym
xsyms
xfindsym

Expression display
xccode
xfortran
xlatex
xpretty

Complex numbers
xconj
xreal
ximag

Extended precision arithmetic
?digits
?vpa
numeric

Expression manipulation
?collect
?expand
xfactor
xhorner
xnumden
xsimple
xsimplify
xsubexpr

Calculus
?diff
differentiate
xint
xjacobian
xlimit
xsymsum
xtaylor

Linear algebra
xcolspace
xdet
xdiag
xeig
xexpm
xinv
xjordan
xnull
xpoly
xrank
xrref
xsvd
xtril
xtriu

Equation solver
xcompose
xdsolve
xfinverse
xsolve

Special functions
xcosint
xhypergeom
xlambertw
xsinint
xzeta

Maple interface
xmaple
xmapleinit
xmfun
xmhelp
xmfunlist
xprocread

Symbolic expression plots
xezcontour
xezcontourf
xezmesh
xezmeshc
xezplot
xezplot3
xezpolar
xezsurf
xezsurfc
xfuntool
xrsums

Conversions
xchar
xdouble
xpoly2sym
xsym2poly

Transforms
xfourier
xifourier
xilaplace
xiztrans
xlaplace
xztrans