cholsl.F90

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!SFX_LIC Copyright 1994-2014 CNRS, Meteo-France and Universite Paul Sabatier
!SFX_LIC This is part of the SURFEX software governed by the CeCILL-C licence
!SFX_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt  
!SFX_LIC for details. version 1.
SUBROUTINE cholsl(N,A,P,B,X)

 USE yomhook   ,ONLY : lhook,   dr_hook
 USE parkind1  ,ONLY : jprb

 IMPLICIT NONE

 INTEGER, INTENT(IN) :: n
 REAL, DIMENSION (N,N),  INTENT(IN) :: a
 REAL, DIMENSION (N),  INTENT(IN)   :: p,b
 REAL, DIMENSION (N), INTENT(INOUT) :: x
 INTEGER :: i
 REAL(KIND=JPRB) :: zhook_handle

 IF (lhook) CALL dr_hook('CHOLSL',0,zhook_handle)

 DO i=1,n
   x(i) = (b(i) - dot_product(a(i,1:i-1),x(1:i-1)))/p(i)
 ENDDO
 DO i=n,1,-1
   x(i) = (x(i) - dot_product(a(i+1:n,i),x(i+1:n)))/p(i)
 ENDDO

 IF (lhook) CALL dr_hook('CHOLSL',1,zhook_handle)

END SUBROUTINE cholsl