Normal/unitary/Hermitian linear operator and its representation matrix lemma

Polar norm equations lemma

Normal linear operator criterion theorem

Unitary linear operator criterion theorem

Unitary linear operator and angles lemma

Examples of unitary operators

Operations preserving matrix unitarity lemma

Unitary matrix and its row/column spaces lemma

Orthogonal matrix definition

Following lemmas are also correct for matrices under standard inner product

Normality after addition with scalar linear operator lemma

Eigenvalues of adjoint linear operator lemma

Orthogonality of eigenvectors of normal linear operator lemma

Unitary linear operator eigenvalues lemma