 which sets up the parameters but does not do
any actual fitting. ncut specifies the cutoff point for filtering, and
should be determined in the same way as for <a
href="filter.html">filter</a>. If <b>ncut</b> is absent, it is
calculated from parameters in the header file, using the number of
points in the interferogram, the position of the central fringe and
the apodization used.  If the latter is identically zero, it is
assumed to be the canonical 10% . nrise is the width in points of the
cosine bell func