Identity matrix
Description
Let be a ring and let be an integer. The identity matrix is the matrix over with entries on the main diagonal and elsewhere. Its entries are , where if and otherwise. For each matrix , and .
Remarks
The identity matrix is the identity element of the matrix ring . It is the matrix of the identity map in any basis. For example, .
Explanations
L1 human
The identity matrix has ones on the diagonal and zeros everywhere else. It plays the role of the number : multiplying by it changes nothing. As a map, it leaves each vector where it is.
What this node needs for W2
- section Invariants: a table of the main invariants (0 of 1)
The writing levels say how complete the text of a node is. They do not measure its truth.
What depends on this
83 nodes use this node, directly or through other nodes.
- Singular value decomposition 000NPTMX6J
- Scaling a row scales the determinant 009CY8JXFX
- Leibniz formula for determinants 016PE4VZ8Q
- Determinant of a scalar multiple 01EXSMK864
- Adding a multiple of one row to another preserves the determinant 01ZTQBK64Q
- Similar matrices 027KDW2K72
- Triangularisation 0363JMQ42Y
- Characteristic polynomial 039HF58KQ5
- Determinant of a linear map 03F5KP94K0
- A matrix is invertible iff its determinant is a unit 03Q7RE2HXR
- Rational canonical form 042JWAR3Q0
- Determinant is multiplicative 04CPJ6AF00
- Spectral theorem for normal matrices 04CW1P44VD
- Determinant as signed volume 04X3PR72VJ
- Product of a matrix and its adjugate 0528HKWZ1Z
- Eigenvalues are the roots of the characteristic polynomial 053QVHF6N7
- A matrix is diagonalisable iff it has a basis of eigenvectors 056SW1E0AC
- Laplace expansion along a column 06AMCJMMVM
- One-sided inverse of a square matrix is two-sided 0753Y2X5K6
- Determinant of the inverse 0783S9D0ZH
- Jordan normal form 085HQ5G5TE
- Existence of an eigenvalue over an algebraically closed field 08CJB2NQ92
- Cauchy–Binet formula 08WE2W7DYS
- Minimal polynomial divides the characteristic polynomial 093X6MN6Y6
- Cramer's rule 0977KZ6PQB
- Permuting rows multiplies the determinant by the sign 09YB3WQG38
- Determinant of a matrix exponential 0A1QQN333A
- Rotation matrix 0B9QNFGTHM
- Matrix determinant lemma 0BC3Q6K92H
- Characteristic polynomial of a linear map 0BZ81AJNWF
- Laplace expansion along a row 0C08BQ3M05
- Determinant is the product of the eigenvalues 0C2F40MEBC
- Determinant 0C3CFHDN6R
- Special orthogonal group 0CGYNDCWRR
- Unitary matrix 0D6RMJ10M9
- Spectral theorem for Hermitian matrices 0DGZBQWZWN
- Inverse in terms of the adjugate 0ENVM493VK
- QR decomposition 0ERWG4NXQ9
- Cayley–Hamilton theorem 0F765KFC2J
- Simultaneous diagonalisation 0FK17N4DKA
- Scalar matrix 0FRM62SG7D
- Trace is a coefficient of the characteristic polynomial 0FRYPZ6D0X
- Determinant of a matrix with a zero row 0FS6B46E5T
- Sylvester's determinant theorem 0G24VQ1088
- Adjugate matrix 0GMPYM0NSR
- Rule of Sarrus 0H8SZFFDXJ
- Polar decomposition 0J2C7BDJQA
- Determinant of a block triangular matrix 0J9TVTNB4K
- Determinant of a triangular matrix 0K1KKMFHYH
- Determinant of a matrix with two equal rows 0K4VQB7HWR
- Determinant via the Schur complement 0KA7A4ENVJ
- Determinant of a linear map is the determinant of its matrix 0KMN32XGPF
- Elementary matrix 0M79HRJCRR
- Diagonalisable iff the minimal polynomial has distinct roots 0MPAJRB23T
- Transvection 0NMN00FNW1
- Trace is the sum of the eigenvalues 0NMXDCNNKR
- Equivalent matrices 0P21AVFFSP
- Vandermonde determinant 0P84B554AS
- Determinant is multilinear in the rows 0PPG793642
- Principal axis theorem 0PR5P9Z4KM
- Orientation of a real vector space 0Q8BZXVT1Z
- Cayley–Hamilton theorem for linear maps 0QEM68Y0DE
- Orthogonal matrix 0QRBVFJ50X
- Unitary group 0R9R0Y1HDK
- Inverse of a product 0S4WTRE9GG
- Algebraic multiplicity 0S7A0EMPF4
- Minor 0SD528P0EK
- Determinant is a coefficient of the characteristic polynomial 0T0X8GTYYS
- Orthogonal group 0TKYAEJ8N7
- Powers of a diagonalisable matrix 0TNR9BQ871
- Invertible matrix 0TWTS88TWN
- Characteristic polynomial does not depend on the basis 0TYMASG33Y
- Determinant of a family of vectors in a basis 0V94H674MB
- Special linear group 0V9PMN0RBH
- Companion matrix 0VH1TC1PWF
- Cartan–Dieudonné theorem 0VMWGYY35Q
- Cofactor 0W2QAVJQ1W
- Sylvester's criterion 0WKEF78PMV
- Diagonalisable matrix 0Y17PEKF24
- Distinct eigenvalues imply diagonalisable 0Y95Z7MT02
- Determinant of the identity matrix 0Z4BWARC38
- Determinant of a 2 by 2 matrix 0ZN2J42SK7
- Determinant of a transpose 0ZZQ2E1MTE
Sources
- Web https://en.wikipedia.org/wiki/Identity_matrix, lead section
What links here
Used by
- Determinant 0C3CFHDN6R
- Unitary matrix 0D6RMJ10M9
- Scalar matrix 0FRM62SG7D
- Sylvester's determinant theorem 0G24VQ1088
- Elementary matrix 0M79HRJCRR
- Orthogonal matrix 0QRBVFJ50X
- Invertible matrix 0TWTS88TWN
- Determinant of the identity matrix 0Z4BWARC38