Editing Gram matrix (section)

===Other properties===
* Because <math>G = G^\dagger</math>, it is necessarily the case that <math>G</math> and <math>G^\dagger</math> commute.  That is, a real or complex Gram matrix <math>G</math> is also a [[normal matrix]].
* The Gram matrix of any [[orthonormal basis]] is the identity matrix.  Equivalently, the Gram matrix of the rows or the columns of a real [[rotation matrix]] is the identity matrix.  Likewise, the Gram matrix of the rows or columns of a [[unitary matrix]] is the identity matrix.
* The rank of the Gram matrix of vectors in <math>\mathbb{R}^k</math> or <math>\mathbb{C}^k</math> equals the dimension of the space [[Linear span|spanned]] by these vectors.<ref name="HJ-7.2.10"/>