lambda_eval_0 Function

      function lambda_eval_0(self, x) result(y)
         implicit none
         ! Arguments
         class(lambda_obj),      intent(inout) :: self
         real(DP), dimension(:), intent(in) :: x
         ! Result
         real(DP)                      :: y
         if (associated(self%lambdaptr)) then
            y = self%lambdaptr(x)
            self%lastval = y
            if (allocated(self%lastarg)) deallocate(self%lastarg)
            allocate(self%lastarg, source=x)
         else
            stop "Lambda function was not initialized"
         end if
      end function lambda_eval_0