Matrix variables

A matrix is a two dimensional array of double precision real numbers, with rows and columns. The row and column indices of a matrix are separated with a comma. The row dimension is specified first. There is no maximum size for matrices.

A literal matrix can be a list of vectors, such as, `[[1;2;3];[4;5;6];[7;8;9]]`, or an expression that results in a matrix, such as `[2:5]><[2:6]`.

The following table shows the possible ways that variables can be considered to be equivalent to matrices, that is, can be used wherever matrices are expected.

Let `x` and `y` be vectors. Suppose that `M` is a matrix.

`M` | = | `M[i,j]` for `i=1,...,VLEN(M)[1], j=1,...,VLEN(M)[2]`
`M[x,y]` | = | `M[i,j]` for `i=x[1],x[2],...,x[#], j=y[1],y[2],...,y[#]`

Vector variables
String variables