Schwinger's variational principle


Schwinger's variational principle

[′shviŋ·ərz ‚ver·ē′ā·shən·əl ‚prin·sə·pəl] (physics) A method used in electromagnetic theory, or similar disciplines, to calculate an approximate value or a linear of quadratic functional, such as a scattering amplitude or reflection coefficient, when the function for which the functional is evaluated is the solution of an integral equation.