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qp2/src/utils_trust_region/trust_region_rho.irp.f

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2023-04-18 13:01:25 +02:00
! Agreement with the model: Rho
! *Compute the ratio : rho = (prev_energy - energy) / (prev_energy - e_model)*
! Rho represents the agreement between the model (the predicted energy
! by the Taylor expansion truncated at the 2nd order) and the real
! energy :
! \begin{equation}
! \rho^{k+1} = \frac{E^{k} - E^{k+1}}{E^{k} - m^{k+1}}
! \end{equation}
! With :
! $E^{k}$ the energy at the previous iteration
! $E^{k+1}$ the energy at the actual iteration
! $m^{k+1}$ the predicted energy for the actual iteration
! (cf. trust_e_model)
! If $\rho \approx 1$, the agreement is good, contrary to $\rho \approx 0$.
! If $\rho \leq 0$ the previous energy is lower than the actual
! energy. We have to cancel the last step and use a smaller trust
! region.
! Here we cancel the last step if $\rho < 0.1$, because even if
! the energy decreases, the agreement is bad, i.e., the Taylor expansion
! truncated at the second order doesn't represent correctly the energy
! landscape. So it's better to cancel the step and restart with a
! smaller trust region.
! Provided in qp_edit:
! | thresh_rho |
! Input:
! | prev_energy | double precision | previous energy (energy before the rotation) |
! | e_model | double precision | predicted energy after the rotation |
! Output:
! | rho | double precision | the agreement between the model (predicted) and the real energy |
! | prev_energy | double precision | if rho >= 0.1 the actual energy becomes the previous energy |
! | | | else the previous energy doesn't change |
! Internal:
! | energy | double precision | energy (real) after the rotation |
! | i | integer | index |
! | t* | double precision | time |
subroutine trust_region_rho(prev_energy, energy,e_model,rho)
include 'pi.h'
!BEGIN_DOC
! Compute rho, the agreement between the predicted criterion/energy and the real one
!END_DOC
implicit none
! Variables
! In
double precision, intent(inout) :: prev_energy
double precision, intent(in) :: e_model, energy
! Out
double precision, intent(out) :: rho
! Internal
double precision :: t1, t2, t3
integer :: i
print*,''
print*,'---Rho_model---'
!call wall_time(t1)
! Rho
! \begin{equation}
! \rho^{k+1} = \frac{E^{k} - E^{k+1}}{E^{k} - m^{k+1}}
! \end{equation}
! In function of $\rho$ th step can be accepted or cancelled.
! If we cancel the last step (k+1), the previous energy (k) doesn't
! change!
! If the step (k+1) is accepted, then the "previous energy" becomes E(k+1)
! Already done in an other subroutine
!if (ABS(prev_energy - e_model) < 1d-12) then
! print*,'WARNING: prev_energy - e_model < 1d-12'
! print*,'=> rho will tend toward infinity'
! print*,'Check you convergence criterion !'
!endif
rho = (prev_energy - energy) / (prev_energy - e_model)
!print*, 'previous energy, prev_energy:', prev_energy
!print*, 'predicted energy, e_model:', e_model
!print*, 'real energy, energy:', energy
!print*, 'prev_energy - energy:', prev_energy - energy
!print*, 'prev_energy - e_model:', prev_energy - e_model
print*, 'Rho:', rho
!print*, 'Threshold for rho:', thresh_rho
! Modification of prev_energy in function of rho
if (rho < thresh_rho) then !0.1) then
! the step is cancelled
print*, 'Rho <', thresh_rho,', the previous energy does not changed'
!print*, 'prev_energy :', prev_energy
else
! the step is accepted
prev_energy = energy
print*, 'Rho >=', thresh_rho,', energy -> prev_energy:', energy
endif
!call wall_time(t2)
!t3 = t2 - t1
!print*,'Time in rho model:', t3
print*,'---End rho_model---'
end subroutine