The Wolfram Language has many matrix operations that support operations such as building, computing, and visualizing matrices. It also has a rich language for picking out and extracting parts of matrices.

Define the following matrix. Note how a matrix in the Wolfram Language is not restricted to number entries:

Use Part to go to the first row and take the second element:

Or use the shorthand notation [[…]] for Part:

To take an entire row, use one index to specify the row:

To take an entire column, you need to select all rows with All and specify the column:

To pick out a submatrix, you can use Span (;;). First, define a 4×5 matrix:

The top-left 3×4 matrix with bold entries here corresponds to rows 1 through 3 and columns 1 through 4:

Extract the highlighted matrix by using Span (;;) to specify the relevant span of rows and columns:

Extract all elements except the outermost rows and columns (negative indices count from the end):