Let (X,Σ,μ)(X,\Sigma,\mu)(X,Σ,μ) be a measure space. The ppp-norm of a measurable function f→Rf \to \mathbb Rf→R is ∣∣f∣∣p=(∫X∣f∣pdμ)1/p.\vert \vert f\vert \vert _p = \left(\int_X \vert f\vert ^p\text d\mu\right)^{1/p}.∣∣f∣∣p=(∫X∣f∣pdμ)1/p.