In linear algebra, the Gram matrix of a set of vectors v 1, …, v n {\displaystyle v_{1},\dots,v_{n}} in an inner product space is the Hermitian matrix of inner products, whose entries are given by the inner product G i j = ⟨ v i, v j ⟩ {\displaystyle G_{ij}=\left\langle v_{i},v_{j}\right\rangle }. Wikipedia