# Definition:Hermitian Matrix

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## Definition

Let $\mathbf A$ be a square matrix over $\C$.

$\mathbf A$ is **Hermitian** if and only if:

- $\mathbf A = \mathbf A^\dagger$

where $\mathbf A^\dagger$ is the Hermitian conjugate of $\mathbf A$.

## Also see

- Definition:Self-Adjoint Operator
- Definition:Symmetric Matrix
- Definition:Unitary Matrix
- Results about
**Hermitian matrices**can be found here.

## Source of Name

This entry was named for Charles Hermite.

## Historical Note

The Hermitian matrix was invented by Charles Hermite to solve certain problems in number theory.

However, it turned out to be crucial in the formulation by Werner Karl Heisenberg of his model of quantum mechanics.

## Sources

- 2008: David Nelson:
*The Penguin Dictionary of Mathematics*(4th ed.) ... (previous) ... (next): Entry:**Hermitian matrix**