# Dual norm

Given the norm is $LaTeX: L_p$, where $LaTeX: p \ge 1$, its dual norm is $LaTeX: L_q$, where $LaTeX: (1/p) + (1/q) = 1$. Note, if $LaTeX: p=1$ then $LaTeX: q=\infty$, and if $LaTeX: q=1$ then $LaTeX: p=\infty$. This is based on Hölder's inequality.