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Viewing Version 12 of 'Jordan canonical form theorem'
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Title of object: Jordan canonical form theorem
Canonical Name: JordanCanonicalFormTheorem
Type: Theorem

Created on: 2002-08-26 10:37:19
Modified on: 2007-11-05 09:39:35

Creator: Mathprof
Modifier: Mathprof
Author: Mathprof
Author: vypertd

Classification: msc:15A18
Defines: Jordan block, Jordan matrix
Synonyms: Jordan canonical form theorem=Jordan canonical form

Revision comment (for changes between this and next version):

Changes for correction #13230 ('\cdots').

Preamble:

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\usepackage{amssymb}
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\newtheorem*{thms}{Theorem}
Content:

A \textbf{Jordan block} or \textbf{Jordan matrix} is a matrix of the form

$$\begin{pmatrix}
\lambda & 1 & 0 & ... & 0\\
0 & \lambda & 1 & ... & 0\\
0 & 0 & \lambda & ... & 0\\
\vdots & \vdots & \vdots & \ddots & 1\\
0 & 0 & 0 & ... & \lambda
\end{pmatrix}$$

with a constant value $\lambda$ along the diagonal and 1's on the superdiagonal. Some texts \PMlinkescapetext{place} the 1's on the subdiagonal instead.




\begin{thms} Let $V$ be a finite-dimensional vector space over a field $F$ and $t:V \to V$ be a linear transformation. Then, if the characteristic polynomial factors completely over $F$, there will exist a basis of $V$ with respect to which the matrix of $t$ is of the form

$$\begin{pmatrix}
J_{1} & 0 & ... & 0\\
0 & J_{2} & ... & 0\\
& & ... & \\
0 & 0 & ... & J_{k}
\end{pmatrix}$$

where each $J_{i}$ is a Jordan block in which $\lambda = \lambda_{i}$.
\end{thms}
The matrix in Theorem 1 is called a \emph{Jordan canonical form} for the transformation \emph{t}.