bedload_direction.f

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!                   **************************************
                    SUBROUTINE bedload_direction ! (_IMP_)
!                   **************************************
!
     &  (qu, qv, npoin, pi, thetac)
!
!***********************************************************************
! SISYPHE   V6P1                                   21/07/2011
!***********************************************************************
!
!brief    COMPUTES THE THETAC ANGLE (FLOW DIRECTION).
!
!history  C. VILLARET
!+        01/10/2003
!+        V5P4
!+
!
!history  N.DURAND (HRW), S.E.BOURBAN (HRW)
!+        13/07/2010
!+        V6P0
!+   Translation of French comments within the FORTRAN sources into
!+   English comments
!
!history  N.DURAND (HRW), S.E.BOURBAN (HRW)
!+        21/08/2010
!+        V6P0
!+   Creation of DOXYGEN tags for automated documentation and
!+   cross-referencing of the FORTRAN sources
!
!history  C.VILLARET (EDF-LNHE), P.TASSI (EDF-LNHE)
!+        19/07/2011
!+        V6P1
!+  Name of variables
!+
!
!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!| NPOIN          |-->| NUMBER OF POINTS
!| PI             |-->| PI
!| QU             |-->| DISCHARGE X
!| QV             |-->| DISCHARGE Y
!| THETAC         |<->| CURRENT ANGLE TO THE X AXIS
!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!
      USE interface_sisyphe,
     &    ex_bedload_direction => bedload_direction
      USE bief
      USE declarations_special
      IMPLICIT NONE
!
      ! 2/ GLOBAL VARIABLES
      ! -------------------
      TYPE(bief_obj),  INTENT(IN)  :: QU, QV
      INTEGER,          INTENT(IN)  :: NPOIN
      DOUBLE PRECISION, INTENT(IN)  :: PI
      TYPE(bief_obj),  INTENT(INOUT) :: THETAC
!
      ! 3/ LOCAL VARIABLES
      ! ------------------
      INTEGER                     :: I
      DOUBLE PRECISION, PARAMETER :: LOCAL_ZERO = 1.d-6
!
!======================================================================!
!======================================================================!
!                    DECLARES TYPES AND DIMENSIONS                     !
!======================================================================!
!======================================================================!
      DO i = 1, npoin
        IF (abs(qu%R(i)) <= local_zero) THEN
          IF (qv%R(i) < = local_zero) THEN
            thetac%R(i) = -pi*0.5d0
          ELSE
            thetac%R(i) =  pi*0.5d0
          ENDIF
        ELSE
          thetac%R(i) = atan(qv%R(i) / qu%R(i))
          IF (qu%R(i) < 0.d0) THEN
            thetac%R(i) = pi + thetac%R(i)
          ENDIF
        ENDIF
      END DO
!======================================================================!
!======================================================================!
      RETURN
      END SUBROUTINE bedload_direction