[daip] DFTPL question/remark

[Eric Greisen]

Hanno Spreeuw wrote:
> Hello,
> 
> The sampling time of the visibilities in my dataset is 5s.
> When I set bpar(2)=5, I get 2879 flux density values.
> When I set bpar(2)=1 or 4.99, I get 3842 flux density values.
> 
> Perhaps this cannot be fixed, but I just wanted to mention it.

The issue is the perennial issue of time binning (esp given that time 
recording is not perfectly accurate).  If an interval starts with a 
sample at T1 does it include all samples <= T1+BPARM(2) or all samples
< T1+BPARM(2)?  The code was the former so I changed it to the latter. 
I put a remark in the help file to provide some guidance.  Since times 
are not perfectly accurate (days in single-precision floating point) 
even this change will probably get you 2 samples averaging together on 
occasion.  The use of 4.9 or 1 is recommended.  To get 2 together most 
of the time (i.e. where possible), a BPARM(2) value like 6 rather than 
10.0 would be recommended.

Eric Greisen