anchor.diff:     
       
       if ( EqualRealNos(phi, 0.0_ReKi) ) then
  -      fzero =  0.0
  -      a     =  0.0
  -      ap    =  0.0
  +      fzero =  0.0_ReKi
  +      a     =  0.0_ReKi
  +      ap    =  0.0_ReKi
  +      chi   =  0.0_ReKi
         return
       end if
       
  
positive.code: 
     F = Ftip * Fhub
  
        ! bem parameters
     k  = sigma_p*Cx/4.0_DbKi/F/sphi/sphi  ! checked GJH
      
  
negative.code: 
      F = Ftip * Fhub
  
      if ( EqualRealNos(F, 0.0_ReKi) ) then
        fzero =  0.0_ReKi
        a     =  1.0_ReKi
        ap    =  -1.0_ReKi
        chi   =  0.0_ReKi
        return
      end if
      
      ! bem parameters
      
  