anchor.diff:  
   REAL, DIMENSION(nnod,ng) ::  osigr, onuf
   REAL, DIMENSION(nnod,ng,ng) :: osigs
  -
  -REAL, DIMENSION(nnod,ng) :: fl       ! To store scalar flux. f0 used to store shape function.
  -REAL, DIMENSION(nnod) :: pline       ! Linear power density
   
   REAL :: A, rho
   
  
positive.code:     !Calculate amplitude function
      CALL point(t1, t2, hp, rho, A, beta, amp)
  
      fl = amp * f0
  
      WRITE(ounit,'(I4, F10.3, F10.4, ES15.4, 12F9.2)') step, t2, rho/tbeta, amp, (bpos(n), n = 1, nb)
  
      IF (stime) EXIT
  
negative.code: REAL :: k1, k2, k3, k4
  REAL :: xtbet
  
  
  itot = INT((tf - ti) / h)
  DO i = 1, itot
  