This method modifies an array $ u $ so that it satisfies the given condition.
This method modifies an operator $ L $ before it is applied to an array $ u $ so that $ v = Lu $ will satisfy the given condition.
This method modifies an operator $ L $ before the linear system $ Lu' = u $ is solved so that $ u' $ will satisfy the given condition.
This method sets the current time for time-dependent boundary conditions.
This method modifies an array $ u $ so that it satisfies the given condition.