perturbation theory(redirected from Pertubation Theory)
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perturbation theory[‚pər·tər′bā·shən ‚thē·ə·rē]
The study of the solutions of differential and partial differential equations from the viewpoint of perturbation of solutions.
The theory of obtaining approximate solutions to the equations of motion of a physical system when these equations differ by a small amount from equations which can be solved exactly.