Subject: A would like to FITS capability in these areas.

From: chaganti at ssl.DNET.NASA.GOV
Date: Fri, 11 Jun 93 15:21:09 EDT

[This posting was sent to the request channel of "fitsbits" -Don]
------- Start of forwarded message -------
From: chaganti at ssl.DNET.NASA.GOV
To: "fitsbits-request at fits.cv.nrao.edu" at EAST.DNET.NASA.GOV
Subject: A would like to FITS capability in these areas.
Date: Thu, 10 Jun 93 14:27:09 -0400

Hallo FITSir,

I would like to know how FITS the following I gave the example for HDF

 APPlications               HDF                    FITS

Language Supported          C,FORTRAN

Inherent data Types         char,short,long
                            int,float,double,
                            string

User-defind types            yes

Dataconversion               XDR,native

Maximum array dimensions     unlimited
Extended array dimensions    yes
Hyperser access              yes
User-definable attributes    yes
Attribute types              any
Named dimensions             yes
Array-index ordering         row,column
sharabality                  yes
Compression                  yes
supporting tools             many (X-window based, SGibased, etc)
supporting machines          sun,vax,mac,ibm,sgi,etc.

Why should we use fits format for astonomy applications?
(because it is accepted by international astronimacal union as standard or
 are there any other reasons) 

How about different machines portability?

Please let me know any more information if you feel important about fits. etc.

I appriciate your help?

The reason for this survay is to find why this many data formats in use?

Thanks in advance
chaganti, kris
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4219-B, Myrtle wood dr.     Email: DECNET : sslmor::chaganti
HUNSVILLE,                         Internet: chaganti at xanth.msfc.nasa.gov
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From: dwells at fits.CV.NRAO.EDU (Don Wells)
Date: Fri, 11 Jun 1993 21:46:30 GMT

In article <9306111921.AA03238 at fits.cv.nrao.edu>
chaganti at ssl.DNET.NASA.GOV writes:
   I would like to [fill in this comparison of] FITS [with] HDF

    APPlications               HDF                    FITS -- answers added:

   Language Supported          C,FORTRAN               N.A. <1>

   Inherent data Types         char,short,long        8-bit unsigned,
			       int,float,double,      16 and 32 2s complement
			       string                 32 and 64 IEEE FP 
                                                      more in BINTABLE <2>

   User-defind types            yes                   yes, in BINTABLE <3>

   Dataconversion               XDR,native            N.A.

   Maximum array dimensions     unlimited             unlimited
   Extended array dimensions    yes              <---define this
   Hyperser access              yes                   "      "
   User-definable attributes    yes                   "      "
   Attribute types              any                   "      "
   Named dimensions             yes                   "      "
   Array-index ordering         row,column            first axis first
   sharabality                  yes               <---define this
   Compression                  yes                   depends <4>
   supporting tools             many (X-window based, SGibased, etc) <---yes
   supporting machines          sun,vax,mac,ibm,sgi,etc. <---yes

FITS is the most effective format for interchanging data between
astronomers separated in space and time (archiving is one-way
interchange with the future) because astronomers everywhere have tools
for manipulating FITS files. In addition, FITS is especially well
adapted to astronomical needs. For example, it supports precise
descriptions of world coordinate systems and tables.

Of course.

   Please let me know any more information if you feel important about
	fits. etc. 

FITS is suitable for use in archives because it is self-describing
(verbose ASCII headers) and because the specifications have been
published in the professional astronomical journals where they will be
readable centuries from now.  HDF, by comparison, is a tagged binary
structure design which depends on a (ephemeral) central authority to
define and control the binary tag codes. 

                -=-

<1> FITS is a canonical *external* format used to interchange data
between datasystems. The FITS format is *not* defined by a subroutine
library, it is language independent. However, libraries do exist;
e.g., the FITSIO library package from tetra.gsfc.nasa.gov is available
in both C and Fortran bindings.

<2> The BINTABLE extension (see /fits/documents/proposals/bintable2.*
on fits.cv.nrao.edu) has codes for logical, bit array, string,
complex, double complex and pointer types, in addition to the set
supported by basic FITS.

<3> The BINTABLE extension is effectively a self-describing syntax for
arrays of arbitrary structs (user-defined types).  A FITS file can
contain an arbitrary number of BINTABLE extensions.

<4> A considerable number of experiments have been done with
compression of astronomical datasets. Some experiments have been done
in the context of FITS (see /fits/documents/drafts/compress.* on
fits.cv.nrao.edu, and also see the "compress" entry in the file
/fits/wais-sources/nrao-fits.src).

--

  Donald C. Wells           Associate Scientist       dwells at nrao.edu
  National Radio Astronomy Observatory                +1-804-296-0277
  520 Edgemont Road                              Fax= +1-804-296-0278
  Charlottesville, Virginia 22903-2475 USA         78:31.1W, 38:02.2N