subroutine asd(
     *  cslagm, cslmin, 
     *  cslmax, chtsmx, cs0ags,
     *  cslagx, c4p, se0, c4m, se1)

c     + + + ARGUMENT DECLARATIONS + + +
      real cslagm, cslmin
      real cslmax, chtsmx, cs0ags
      real cslagx, c4p, se0, c4m, se1

c  ASD SECTION:
c      calc. slope parameter using prior geometric mean dia.
C ***      write(*,*) "asd: ",c4m,(cslagm-cslmin),(cslmax-cslmin)
C *** debugging fix
      if (cslagm.le.cslmin) then
         cslagm = cslmin
         c4m = 0.5
      else
         c4m = sqrt((cslagm - cslmin)/
     *     (cslmax - cslmin))*(1.0/se0)
         if (c4m .lt. 0.5) c4m = 0.5
         if (c4m .gt. 2.0) c4m = 2.0
      endif
C *** eodf
C ***      write(*,*) "asd: ",c4m,(cslagm-cslmin),(cslmax-cslmin)

c     calc. new geom. mean dia.

          cslagm = cslmin + (cslmax - cslmin)*
     *      (c4m*se1)**2.

c     restrict upper size if not frozen
         if ((chtsmx .ge. 0.0) .and. 
     *     (cslagm .gt. cslmax)) then
            cslagm = cslmax
         endif

c     calc geom. standard deviation (eq. S-49)
         cs0ags = 1.0 / (0.0203 + 0.00193  *cslagm +
     &             0.074 / sqrt(cslagm))

c     calc. max. diameter for asd
         c4p = 1.52 * cslagm**(-0.449)
C ***      write(*,*) ' c4p ', c4p
         cslagx = cslagm * cs0ags**c4p
      end