The Dirichlet energy of a real-valued harmonic function 
on a bounded domain 
is 
, where 
is the gradient.
Dirichlet Energy
See also
EnergyExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Dirichlet Energy." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/DirichletEnergy.html