ObserverUpdateOneStep Subroutine

    Subroutine ObserverUpdateOneStep(self, mesh, BufferPosition, isSolid, tsource)

      implicit none

      class (ObserverClass)                                :: self
      class (HexMesh), intent(in)                          :: mesh
      integer,intent(in)                                   :: bufferPosition
      logical, intent(in)                                  :: isSolid
      real(kind=RP), intent(in)                            :: tsource

      ! local variables
      real(kind=RP)                                        :: tobserver
      integer                                              :: i
      integer, dimension(self%numberOfFaces)               :: nDiscard

      ! store the solution of each pair at the last position, by not giving the bufferPosition
      call self % update(mesh, isSolid, interpolate=.TRUE.)

      ! interpolate the solution of each pair at first position
      ! and save the time of each pair at its last position
      tobserver = tsource + self % tDelay
!$omp parallel shared(self)
!$omp do schedule(runtime)
      do i = 1, self % numberOfFaces
            if (self % sourcePair(i) % tDelay .eq. self % tDelay) cycle
            call self % sourcePair(i) % interpolateSolS(tobserver, tsource)
      end do 
!$omp end do
!$omp end parallel

      ! sum all the pair solution and save it at bufferPosition of the observer sol
      nDiscard = 0
      call self % sumIntegrals(nDiscard, 1, bufferPosition, bufferPosition)

      ! update the solution of each pair and its times for next iteration
!$omp parallel shared(self)
!$omp do schedule(runtime)
      do i = 1, self % numberOfFaces
            call self % sourcePair(i) % updateOneStep()
      end do 
!$omp end do
!$omp end parallel

    End Subroutine ObserverUpdateOneStep