c     file name: aggs.for

      subroutine aggs( ak, bseagg, semin, semax )

c     + + + PURPOSE + + +
c calculate the agg stability for the different processes from eq. S(54), S(53).

c     + + + AUTHOR + + +
c     Imam Elminyawi

c     + + + KEY WORDS + + +
C     wind erosion, soil processes, ....

c     + + + ARGUMENT DECLARATIONS + + +
      real ak, bseagg, semin, semax

c     + + + LOCAL VARIABLES + + +
      real anc

c     + + + LOCAL DEFINITIONS + + +
c     anc

c     + + + END SPECIFICATIONS + + +


      anc = 0.0
      if ( bseagg .ge. semax .or. bseagg .le. semin) go to 100
         anc = -ak * alog(( bseagg - semin) / (semax - semin) ) + 1.0
         bseagg = (semax - semin) * exp(-anc/ak) + semin
 100  continue

      return
      end