Re: [Opengrads-devel] errors on sdfopen with hdf

[Arlindo da S. <da...@al...>]

On Feb 6, 2008 10:44 AM, Jennifer Adams <jm...@co...> wrote:

>
> Arlindo,
> I have put some print statments in gasdf.c to see why this is happening.
> The HDF routine SDdiminfo returns the following information on
> model.hdf:
>
> dim_id,name,dimsize,dtype,ndatts = 327680 time 0 6 1
> dim_id,name,dimsize,dtype,ndatts = 327681 longitude 72 6 2
> dim_id,name,dimsize,dtype,ndatts = 327682 latitude 46 6 2
> dim_id,name,dimsize,dtype,ndatts = 327683 levels 7 6 5
>
> Looks like the file has a time dimension of size 0. I remember now
> that when I discovered this during development, I put in the
> following line:
>        if (dimsize==0) dimsize=1; /* would you have a coordinate axis with
> size==0 */
>
> The interesting thing is that when I run ncdump (from the HDF4.2r2
> library build) it gives me this:
>
> dimensions:
>         time = UNLIMITED ; // (5 currently)
>         longitude = 72 ;
>         latitude = 46 ;
>         levels = 7 ;
>

It is possible that this is a bug in the SD interface. Ncdump uses the "NC"
interface which is sometimes a more basic, low level interface than SD.  (I
say "sometimes" because the hdf-4 is not so cleanly layered). I suspect that
your ctl/"DTYPE hdf" interface will have similar problems, correct?

The file "model.hdf" was written with the "NC" interface through LATS.
Leading to this version of hdf-4, I reported a couple of bugs to THG in the
hrepack utility which  did not work properly with HDF files written by the
"NC" interface (all GMAO files are written that way, although LATS is not
involved).  It is very possible that this is another one of those bugs.

We have 2 options, report the bug to the THG (we will need a small example
demonstrating the problem), or try to dig in the hdf-4 sources and
contribute a patch to them. They have usually being very responsive to my
bug reports. What do you prefer?

   Arlindo

-- 
Arlindo da Silva
da...@al...