Generalized Rayleigh quotient ($\frac{x^{T}Ax}{x^{T}Bx}$)

For symmetric $A$ and positive-definite $B$, the generalized Rayleigh quotient is $x^{T}Ax/(x^{T}Bx)$. Its stationary values are the generalized eigenvalues of $Av=\lambda Bv$, and its maximum is the largest such eigenvalue.