Multiple indexing is done by including a pair of square brackets inside a pair of parenthesis, ([]).  The result is a vector or matrix.

> x = [1, 2, 3, 4];

> print(x([2,4])) // get second & fourth item as an array

[Matrix] 1 x 2

2      4

For a matrix, the above is accessed using linear indexing.

A range of elements can also be accessed using the colon (:) operator.

> x = [1, 2, 3, 4];

> print(x([2:4])) // get 2nd through 4th items as an array

[Matrix] (1 x 3)

2        3        4

For a matrix, this can be used to extract specific items, such as specific rows or columns.

> x = [1, 2, 3; 4, 5, 6; 7, 8, 9]; print(x)

[Matrix] (3 x 3)

1        2        3

4        5        6

7        8        9

> print(x([1,3],2)) // get 2nd column in rows 1 & 3, as a column vector

[Matrix] (2 x 1)

2

8

> print(x([1,3],[2,3])) // get 2nd & 3rd column in rows 1 & 3

[Matrix] (2 x 2)

2        3

8        9

> print(x([1,3],[1:3])) // get columns 1 to 3 in rows 1 & 3

[Matrix] (2 x 3)

1        2        3

7        8        9

A colon (:) can be used to denote all items in a given dimension.

> print(x([1,3],:)) // get all columns in rows 1 & 3

[Matrix] (2 x 3)

1        2        3

7        8        9

Entire rows or columns can be removed by making them empty.

> x([1,3],:) = []; print(x); // removes rows 1 & 3

[Matrix] 1 x 3

4    5     6