# name of matrix of inner products $\langle f_i, f_j\rangle$

Given a Hilbert space $H$ and a number of elements $\phi_i\in H$, does the matrix $M$ with $$M_{i,j} := \langle\phi_i, \phi_j\rangle$$ have any particular name?

• in finite dimension it is called the Gram matrix Nov 28, 2013 at 19:22

That matrix is called the Gram-matrix of the vectors $\{ \phi_i \}$.