Wirtinger's representation and projection theorem

Wirtinger's representation theorem and projection theorem are fundamental results in mathematical analysis, particularly in the fields of functional analysis and the theory of Sobolev spaces. They are often applied in the study of harmonic functions, the solution of partial differential equations, and variational problems. ### Wirtinger's Representation Theorem: The Wirtinger representation theorem provides a way to connect the Dirichlet energy of functions to their boundary conditions.