anchor.diff:  IMPLICIT NONE
   
   INTEGER, INTENT(IN) :: gt
  -REAL, DIMENSION(:), INTENT(INOUT) :: s, sx1, sy1, sz1
  -REAL, DIMENSION(:), INTENT(INOUT) :: sx2, sy2, sz2
  +REAL, DIMENSION(:), INTENT(OUT) :: s, sx1, sy1, sz1
  +REAL, DIMENSION(:), INTENT(OUT) :: sx2, sy2, sz2
   
   INTEGER :: h, n
  +
  +s = 0.; sx1 = 0.; sy1 = 0.; sz1 = 0.
  +sx2 = 0.; sy2 = 0.; sz2 = 0.
   
   DO h = 1, ng
       DO n = 1, nnod
  
positive.code: 
  Integrate = 0.
  DO n = 1, nnod
      Integrate = Integrate + xdel(ix(n))*ydel(iy(n))*zdel(iz(n)) * s(n)
  END DO
  
  END FUNCTION Integrate
  
negative.code:     Keo = Ke
      erro = errn
      DO g = ng,1,-1
  
          !!!Calculate Scattering source
          CALL SSrcAd(g, ss0, ssx1, ssy1, ssz1, ssx2, ssy2, ssz2)
  