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c
c
      subroutine rough 
     i              (rrimpl,intens,perctill, 
     o               rro) 


c     + + + PURPOSE + + +
c     
c     This subroutine performs a random roughness calculation 
c     after a tillage operation.
c     
c
c
c
c     + + + KEYWORDS + + +
c     random roughness (RR), tillage (primary/secondary)
c
c     + + + ARGUMENT DECLARATIONS + + +
c
	  real perctill,rrimpl,rro,intens       
c
c     + + + ARGUMENT DEFINITIONS + + +
c
c     perctill	- Fraction of the surface tilled
c	  intens	- Tillage intensity factor
c     rrimpl	- Assigned nominal RR value for the tillage operation (mm) 
c     rro		- Pre-tillage surface random roughness (mm) 
c
c     + + + ACCESSED COMMON BLOCK VARIABLE DEFINITIONS + + +
c     
c
c     + + + PARAMETERS + + +
c
c     + + + LOCAL VARIABLES + + +
c
	  real rrf       
c
c     + + + LOCAL VARIABLE DEFINITIONS + + +
c
c     rrf		- Final tilled surface random roughness (mm)
c
c     + + + END SPECIFICATIONS + + + 
c
c	  Perform the calculation of the surface RR after a tillage
c     operation.  Check to see if the tillage intensity factor is
c     needed before performing the calculation. 
c
	  if (rrimpl .ge. rro) then
	    rrf = perctill*rrimpl + (1.0-perctill)*rro
c        print *, 'rrf =',rrf
	  else
		rrf = perctill*(intens*rrimpl + (1.0-intens)*rro) + 
     +        (1.0-perctill)*rro
c        print *, 'rrf =',rrf
	  endif
	  rro = rrf
	  end