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Determinants can also be defined by some of their properties. Namely, the determinant is the unique function defined on the n × n matrices that has the four following properties: The determinant of the identity matrix is 1. The exchange of two rows multiplies the determinant by −1.
The Jacobian determinant is sometimes simply referred to as "the Jacobian". The Jacobian determinant at a given point gives important information about the behavior of f near that point. For instance, the continuously differentiable function f is invertible near a point p ∈ R n if the Jacobian determinant at p is non-zero.
The determinant of the Hessian matrix, when evaluated at a critical point of a function, is equal to the Gaussian curvature of the function considered as a manifold. The eigenvalues of the Hessian at that point are the principal curvatures of the function, and the eigenvectors are the principal directions of curvature.
Examples include (but not limited to) symmetric, skew-symmetric, and normal matrices. Null-Hermitian matrix A square matrix whose null space (or kernel) is equal to its conjugate transpose, N(A)=N(A *) or ker(A)=ker(A *). Synonym for kernel-Hermitian matrices. Examples include (but not limited) to Hermitian, skew-Hermitian matrices, and normal ...
Any property of matrices that is preserved under matrix products and inverses can be used to define further matrix groups. For example, matrices with a given size and with a determinant of 1 form a subgroup of (that is, a smaller group contained in) their general linear group, called a special linear group. [67]
When n > m the determinant and volume are zero. When n = m, this reduces to the standard theorem that the absolute value of the determinant of n n-dimensional vectors is the n-dimensional volume. The Gram determinant is also useful for computing the volume of the simplex formed by the vectors; its volume is Volume(parallelotope) / n!.
For example, the determinant of an n × n matrix is an SL(n) 2 invariant and Cayley's hyperdeterminant for a 2 × 2 × 2 hypermatrix is an SL(2) 3 invariant. A more familiar property of a determinant is that if you add a multiple of a row (or column) to a different row (or column) of a square matrix then its determinant is unchanged.
There is a determinant map from the matrix ring GL(R ) to the abelianised unit group R × ab with the following properties: [1] The determinant is invariant under elementary row operations; The determinant of the identity matrix is 1; If a row is left multiplied by a in R × then the determinant is left multiplied by a