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## Subscripts:   [ ]

select submatrices

matrix[rows,columns]
matrix[elements]

Subscripts are used with matrices to select submatrices, where rows and columns are expressions that evaluate to scalars or numeric vectors. These expressions contain valid subscript values of rows and columns in the argument matrix. A subscripted matrix can appear on the left side of the equal sign. The dimensions of the target submatrix must conform to the dimensions of the source matrix. See Chapter 4, "Working with Matrices," for further information.

For example, the statements

```   x={1 2 3,
4 5 6,
7 8 9};
a=3;
m=x[2,a];
```
select the element in the second row and third column of X and produce the matrix M:
```               M             1 row      1 col    (numeric)

6
```
The statements
```   a=1:3;
m=x[2,a];
```
select row 2, and columns 1 through 3 of X, producing the matrix M:
```               M             1 row      3 cols    (numeric)

4         5         6
```

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