Specific entries of a matrix are often referenced by using pairs of subscripts, for the numbers at each of the rows & columns.

In mathematics, a matrix (plural: matrices) is a rectangle of numbers, arranged in rows and columns. The rows are each left-to-right (horizontal) lines, and the columns go top-to-bottom (vertical). The top-left cell is at row 1, column 1 (see diagram at right).

Matrices are often represented by capital roman letters such as \displaystyle{ A }, \displaystyle{ B } and \displaystyle{ C }, and there are rules for adding, subtracting and "multiplying" matrices together, but the rules are different than for numbers. As an example, the product \displaystyle{ AB } does not always give the same result as \displaystyle{ BA }, which is the case for the multiplication of ordinary numbers. A matrix can have more than 2 dimensions, such as a 3D matrix. Also, a matrix can be one-dimensional, as a single row or a single column.