Difference between revisions of "Identity matrix"
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(New page: In mathematics the '''identity matrix''' is the which does not change the size or values of a matrix under the operation of multiplication. The usually identity matrix is denoted <math>I</...) |
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| − | In mathematics the '''identity matrix''' is the which does not change the size or values of | + | In mathematics the '''identity matrix''' is the [[matrix]] which, when [[multiplication|multiplying]], does not change the size or values of the matrix by which it is multiplied. The identity matrix is usually denoted <math>I</math> or <math>I_n</math>, and the operation of multiplication is described as, |
:<math>AI=A</math> or <math>IA=A</math> | :<math>AI=A</math> or <math>IA=A</math> | ||
| − | The identity matrix is an <math>n\times n</math> | + | The identity matrix is an <math>n\times n</math> matrix where the leading diagonal is ones and all other entries are zero. That is, <math>a_{ii} = 1</math>, and <math>a_{ij} = 0</math> whenever <math>i \neq j</math>. |
:<math>I=\begin{bmatrix} | :<math>I=\begin{bmatrix} | ||
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\vdots & \vdots & \ddots & \vdots \\ | \vdots & \vdots & \ddots & \vdots \\ | ||
0 & 0 & \cdots & 1 \end{bmatrix} | 0 & 0 & \cdots & 1 \end{bmatrix} | ||
| − | </math> | + | </math> |
| − | [[Category: | + | [[Category:Linear Algebra]] |
Latest revision as of 14:34, July 28, 2016
In mathematics the identity matrix is the matrix which, when multiplying, does not change the size or values of the matrix by which it is multiplied. The identity matrix is usually denoted <math>I</math> or <math>I_n</math>, and the operation of multiplication is described as,
- <math>AI=A</math> or <math>IA=A</math>
The identity matrix is an <math>n\times n</math> matrix where the leading diagonal is ones and all other entries are zero. That is, <math>a_{ii} = 1</math>, and <math>a_{ij} = 0</math> whenever <math>i \neq j</math>.
- <math>I=\begin{bmatrix}
1 & 0 & \cdots & 0 \\ 0 & 1 & \cdots & 0 \\ \vdots & \vdots & \ddots & \vdots \\ 0 & 0 & \cdots & 1 \end{bmatrix} </math>