A “matrix” is a grid, or table, of numbers. For instance, the following matrix represents the prices at the store “Nuthin’ But Bed Stuff.”

King-sized | Queen-sized | Twin | |
---|---|---|---|

Mattress | $649 | $579 | $500 |

Box spring | $350 | $250 | $200 |

Fitted sheet | $15 | $12 | $10 |

Top sheet | $15 | $12 | $10 |

Blanket | $20 | $20 | $15 |

(The matrix is the numbers, not the words that label them.)

Of course, these prices could be displayed in a simple list: “King-sized mattress,” “Queen-sized mattress,” and so on. However, this two-dimensional display makes it much easier to compare the prices of mattresses to box springs, or the prices of king-sized items to queen-sized items, for instance.

Each horizontal list of numbers is referred to as a *row;* each vertical list is a *column.* Hence, the list of all mattresses is a row; the list of all king-sized prices is a column. (It’s easy to remember which is which if you think of Greek columns, which are big posts that hold up buildings and are very tall and...well, you know...vertical.) This particular matrix has 5 rows and 3 columns. It is therefore referred to as a 5×3 (read, “5 by 3”) matrix.

If a matrix has the same number of columns as rows, it is referred to as a *square matrix*.

Comments:"DAISY and BRF versions of this collection are available."