Mathematics

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

Trigonometry
*sin
*sinh
*asin
*asinh
*cos
*cosh
*acos
*acosh
*tan
*tanh
*atan
*atan2
*atanh
*sec
*sech
*asec
*asech
*csc
*csch
*acsc
*acsch
*cot
*coth
*acot
*acoth

Exponentials
*exp
*log
*log10
*log2
*pow2
*sqrt
*nextpow2

Complex numbers
*abs
*angle
+complex
Paul Kienzle; == x+1i*y
*conj
*imag
*real
+unwrap
Bill Lash
+isreal
Paul Kienzle, but properly in 2.1.x
+cplxpair
Paul Kienzle

Floating point operations
*fix
*floor
*ceil
*round
*sign

Special functions
*airy
*besselj
*bessely
*besselh
*besseli
*besselk
*beta
*betainc
?betaln
Netlib, FORTRAN, not yet adapted for use in Octave
+ellipj
Paul Kienzle, modified from David Billinghurst
+ellipke
Paul Kienzle, modified from David Billinghurst
*erf
*erfc
?erfcx
Netlib, FORTRAN, not yet adapted for use in Octave
*erfinv
?expint
Netlib, FORTRAN, not yet adapted for use in Octave
*gamma
*gammainc
+gammaln
Paul Kienzle; Octave uses lgamma()
For complex arguments (not handled by matlab either), use cgamma,cgammaln from the old octave-ci database. These should be integrated into the octave gamma and lgamma functions.
+legendre
Kai Habel
+cross
extended for nx3 matices by Kai Habel

Number theory
+mod
Paul Kienzle
*rem
+factor
Paul Kienzle
+isprime
Paul Kienzle
+primes
Paul Kienzle
*gcd
*lcm
xrat
xrats
+perms
Paul Kienzle
+nchoosek
Paul Kienzle
+factorial
Paul Kienzle, ==prod(2:n), ==round(gamma(n+1))

Coordinate transformations
+cart2sph
+cart2pol
+pol2cart
+sph2cart
Kai Habel