The following cmavo are discussed in this section:
jo'i 
JOhI 
start vector 
te'u 
TEhU 
end vector 
pi'a 
VUhU 
matrix row combiner 
sa'i 
VUhU 
matrix column combiner 
A mathematical vector is a list of numbers, and a mathematical matrix is a table of numbers. Lojban considers matrices to be built up out of vectors, which are in turn built up out of operands.
jo'i, the only cmavo of selma'o JOhI, is the vector indicator: it has a syntax reminiscent of a forethought operator, but has very high precedence. The components must be simple operands rather than full expressions (unless parenthesized). A vector can have any number of components; te'u is the elidable terminator. An example:
li  jo'i  paboi  reboi  te'u  su'i  jo'i  ciboi  voboi 
Thenumber  array  (one,  two  )  plus  array  (three,  four) 
du  li  jo'i  voboi  xaboi  
equals  thenumber  array  (four,  six).  
(1,2) + (3,4) = (4,6)

Vectors can be combined into matrices using either pi'a, the matrix row operator, or sa'i, the matrix column operator. The first combines vectors representing rows of the matrix, and the second combines vectors representing columns of the matrix. Both of them allow any number of arguments: additional arguments are tacked on with the null operator ge'a.
Therefore, the “magic square” matrix
8  1  6 
3  5  7 
4  9  2 
can be represented either as:
jo'i  biboi  paboi  xa  pi'a  jo'i  ciboi  muboi  ze 
thevector  (8  1  6)  matrixrow  thevector  (3  5  7), 
ge'a  jo'i  voboi  soboi  re 
thevector  (4  9  2) 
or as
jo'i  biboi  ciboi  vo  sa'i  jo'i  paboi  muboi  so 
thevector  (8  3  4)  matrixcolumn  thevector  (1  5  9), 
ge'a  jo'i  xaboi  zeboi  re 
thevector  (6  7  2) 
The regular mekso operators can be applied to vectors and to matrices, since grammatically both of these are expressions. It is usually necessary to parenthesize matrices when used with operators in order to avoid incorrect groupings. There are no VUhU operators for the matrix operators of inner or outer products, but appropriate operators can be created using a suitable symbolic lerfu word or string prefixed by ma'o.
Matrices of more than two dimensions can be built up using either pi'a or sa'i with an appropriate subscript numbering the dimension. When subscripted, there is no difference between pi'a and sa'i.