!!  Copyright (C)  Stichting Deltares, 2012-2014.
!!
!!  This program is free software: you can redistribute it and/or modify
!!  it under the terms of the GNU General Public License version 3,
!!  as published by the Free Software Foundation.
!!
!!  This program is distributed in the hope that it will be useful,
!!  but WITHOUT ANY WARRANTY; without even the implied warranty of
!!  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
!!  GNU General Public License for more details.
!!
!!  You should have received a copy of the GNU General Public License
!!  along with this program. If not, see <http://www.gnu.org/licenses/>.
!!
!!  contact: delft3d.support@deltares.nl
!!  Stichting Deltares
!!  P.O. Box 177
!!  2600 MH Delft, The Netherlands
!!
!!  All indications and logos of, and references to registered trademarks
!!  of Stichting Deltares remain the property of Stichting Deltares. All
!!  rights reserved.

      subroutine dlalg  ( pmsa   , fl     , ipoint , increm , noseg  ,
     &                    noflux , iexpnt , iknmrk , noq1   , noq2   ,
     &                    noq3   , noq4   )
!>\file
!>       Daylength function for algae DYNAMO

C**********************************************************************
C     +----------------------------------------+
C     |    D E L F T   H Y D R A U L I C S     |
C     |    WAter Resources and Environment     |
C     +----------------------------------------+
C
C***********************************************************************
C
C     Project : STANDAARDISATIE PROCES FORMULES T721.72
C     Author  : Pascal Boderie
C     Date    : 921210             Version : 0.01
C
C     History :
C
C     Date    Author          Description
C     ------  --------------  -----------------------------------
C     ......  ..............  ..............................
C     921210  Pascal Boderie  Create first version, based on T721.13
C                             created by Jos van Gils
C     921229  Pascal Boderie  Add third algae type, nutrient ratio's
C                             per species
C
C***********************************************************************
C
C     Description of the module :
C
C Name    T   L I/O   Description                                   Unit
C ----    --- -  -    -------------------                            ---
C DL      R*4 1 I daylength (sunrise to sunset)                     [D]
C KMDL    R*4 1 I daylength for growth saturation green-algea       [D]

C     Logical Units : -

C     Modules called : -

C     Name     Type   Library
C     ------   -----  ------------

      IMPLICIT REAL (A-H,J-Z)

      REAL     PMSA  ( * ) , FL    (*)
      INTEGER  IPOINT( * ) , INCREM(*) , NOSEG , NOFLUX,
     +         IEXPNT(4,*) , IKNMRK(*) , NOQ1, NOQ2, NOQ3, NOQ4

      IP1  = IPOINT( 1)
      IP2  = IPOINT( 2)
      IP3  = IPOINT( 3)
C
      IFLUX = 0
      DO 9000 ISEG = 1 , NOSEG
!!    CALL DHKMRK(1,IKNMRK(ISEG),IKMRK1)
!!    IF (IKMRK1.GT.0) THEN
      IF (BTEST(IKNMRK(ISEG),0)) THEN
C

      DL        = PMSA(IP1 )
      KMDL      = PMSA(IP2 )

      IF (DL .LT. 1E-20 )  CALL ERRSYS ('DL in DLALG zero', 1 )

C     Actueel licht / licht voor groei verzadiging
      PMSA(IP3 )   =  MIN ( DL, KMDL) / KMDL

      ENDIF
C
      IFLUX = IFLUX + NOFLUX
      IP1   = IP1   + INCREM (  1 )
      IP2   = IP2   + INCREM (  2 )
      IP3   = IP3   + INCREM (  3 )
c
 9000 CONTINUE
c
      RETURN
      END