# Engineering Analysis/Matrix Forms

Matrices that follow certain predefined formats are useful in a number of computations. We will discuss some of the common matrix formats here. Later chapters will show how these formats are used in calculations and analysis.

## Contents

## Diagonal Matrix[edit]

A diagonal matrix is a matrix such that:

In otherwords, all the elements off the main diagonal are zero, and the diagonal elements may be (but don't need to be) non-zero.

## Companion Form Matrix[edit]

If we have the following characteristic polynomial for a matrix:

We can create a **companion form** matrix in one of two ways:

Or, we can also write it as:

## Jordan Canonical Form[edit]

To discuss the Jordan canonical form, we first need to introduce the idea of the **Jordan Block**:

### Jordan Blocks[edit]

A jordan block is a square matrix such that all the diagonal elements are equal, and all the super-diagonal elements (the elements directly above the diagonal elements) are all 1. To illustrate this, here is an example of an n-dimensional jordan block:

### Canonical Form[edit]

A square matrix is in **Jordan Canonical form**, if it is a diagonal matrix, or if it has one of the following two block-diagonal forms:

Or:

The where the D element is a diagonal block matrix, and the J blocks are in Jordan block form.