[daip] Limited number of visibilities in AIPS ?

[Eric Greisen]

Arnaud Collioud wrote:
>
> The IYA09 session is like a normal IVS RDV session, excepted the number of participating stations.  This means I have:
> * 1 polarisation (RR)
> * 4 IFs at X-Band, 4 IFs at S-Band
> * 16 spectra channels per IF (<-- I am not about this point)
> * I am compressing the data (DOUVCOMP=1)

4 bytes * (8 IFs * 16 channels + 10 random parameters) * 6000000 is 
about 3 * 2^30 or more bytes than can be counted in a 32-bit integer.

That said, MK4IN does not occur in our distributed AIPS.  The closest we 
have is MK3IN.  The AIPS routines that handle file sizes (.e.g. ZCREAT, 
ZEXPND) take an argument in kilobytes giving us 2^41 -1 bytes for file 
sizes.  So far we are okay.  I notice in MK3IN there are a number of 
places that use the variable FILSIZ as the size of the file in 
visibility records.  However, that variable is used to call ZEXIST which 
returns the size in kilobytes and then
      filsiz = (filsiz * 256.0D0) / lrec
This depends on the compiler allowing the promotion of filsiz*256.d0 to 
double precision.  Our Intel optimizer would probably revert this to 
integer and so get the wrong answer!  I do not know where MK4IN that you 
are using came from or what compiler was used.  The subroutine MK3XPN is 
used in MK3IN to expand the file and that may be where things are going 
wrong.

I'm sorry but I cannot help further with the old version and unknown task.

Eric Greisen