PeriodicBoundaryCondition

PeriodicBoundaryCondition[u[x1,…],pred,f] represents a periodic boundary condition =u(xtarget)=u(f(xtarget)) for all xtarget on the boundary of the region given to NDSolve where pred is True.

PeriodicBoundaryCondition[a+b u[x1,…],pred,f] represents a generalized periodic boundary condition a+b u(xtarget)=u(f(xtarget)).

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