bracket product

The L^2-inner product of two real functions f and g on a measure space X with respect to the measure μ is given by 〈f, g〉_L^2 = integral_X f g d μ, sometimes also called the bracket product, where the symbol 〈f, g〉 are called angle brackets. If the functions are complex, the generalization of the Hermitian inner product integral_X fg^_ d μ is used.

angle bracket | bra | Hilbert space | inner product | ket | L^2-function | L^2-space | Lebesgue integral