anchor.diff:  c     nf   = number of frequency points in which the spectrum is computed
   c     fmin = minimum frequency (MUST be > 0)
   c     df   = frequency step
  -c     nb   = number of bins in the folded time series at any test period
  -c     qmi  = minimum fractional transit length to be tested
  -c     qma  = maximum fractional transit length to be tested
  +c     nbins   = number of bins in the folded time series at any test period
  +c     qmin  = minimum fractional transit length to be tested
  +c     qmax  = maximum fractional transit length to be tested
   c
   c     Output parameters:
   c     ~~~~~~~~~~~~~~~~~~
  
positive.code:             ph     = u(i)*f0
              ph     = ph-idint(ph)
  c
              j      = 1 + idint(nb*ph)
              ibi(j) = ibi(j) + 1
              y(j) =   y(j) + v(i)
   102     continue
  c
  c-----------------------------------------------
  c     Extend the arrays  ibi()  and  y() beyond
  c     nb   by  wrapping
  c
           do 104 j=nb1,nbkma
              jnb    = j-nb
              ibi(j) = ibi(jnb)
              y(j) =   y(jnb)
   104     continue
  
negative.code: c
           power=0.0d0
  c
           do 1 i=1,nbins
              s     = 0.0d0
              k     = 0
              kk    = 0
  