upgrade Subroutine

  subroutine upgrade(cube, params, power, n_gauss, dim_v, maxiter, m, iprint)
    !! Upgrade parameters (spectra to spectra) using minimize function (here based on L-BFGS-B optimization module)
    implicit none

    real(xp), intent(in), dimension(:,:,:), allocatable :: cube !! cube
    integer, intent(in) :: power !! nside of the cube
    integer, intent(in) :: n_gauss !! number of Gaussian
    integer, intent(in) :: dim_v !! dimension along v axis
    integer, intent(in) :: maxiter !! max number of iteration
    integer, intent(in) :: m !! number of corrections used in the limited memory matrix by LBFGS-B
    integer, intent(in) :: iprint !! print option

    real(xp), intent(inout), dimension(:,:,:), allocatable :: params !! cube parameters to update

    integer :: i,j
    real(xp), dimension(:), allocatable :: line
    real(xp), dimension(:), allocatable :: x
    real(xp), dimension(:), allocatable :: lb, ub

    do i=1, power
       do j=1, power
          ! print*, (i-1)*power+j, " / ", power*power
          allocate(line(dim_v))
          allocate(x(3*n_gauss), lb(3*n_gauss), ub(3*n_gauss))

          line = cube(:,i,j)
          x = params(:,i,j)
          
          call init_bounds(line, n_gauss, dim_v, lb, ub)
          call minimize_spec(3*n_gauss, m, x, lb, ub, line, dim_v, n_gauss, maxiter, iprint)
          
          params(:,i,j) = x
          
          deallocate(line)
          deallocate(x, lb, ub)
       end do
    end do
  end subroutine upgrade