Current limit of 4 decimal digits of DC DFT frequencies is much to low:
If one looks at the real long periodic var stars like e.g. alf Ori,
eps Aur, ... the longest detected periods are in the range of 10000d.
The outburst cycle of RNe can and is often even a multiple of this
So the number of significant digits in the DFT frequency output of
0.0001 1/d = 1/10000d is much too less and one cann't use the DFT
for such long periods as the effective period sequence with this
resolution is just:
indefinite=1/0.0000, 10000d=1/0.0001, 5000d=1/0.0002, 3333d=1/0.0003,
2500d=1/0.0004, ... . Smaller frequencies than 0.0001 1/d are always
rounded to 0.0000 1/d, no matter how long they actually are. As the
DFT plot are also just plotted to 0.0001d resolution, they cann't il-
lustrate such long periods at all.