tion applied to the ends of the data before it is
transformed for filtering. This is to prevent end effects, and values
of nop/10 (usually 400) are normally sufficient (see mask for
details). If a valid .hdr file does not exist (e.g., the data came in
through readcards, not datain), then both nrise and ncut must be
specified.<p>

A filtered lsqfit is preferable to filtering the data and then
executing <b>lsqfit</b> as filtering changes the width and intensity of
the line, whereas a filtered lsqfit will rese