The codes you write do not exist in isolation, and at some point you will have to read data from, or write it to, files. You might, therefore, need to read or write one of a number of standard data formats. Clive Davenhall wrote an article on this in the September 1998 issue of the Starlink Bulletin. This covered reading and writing using the IMG library (SUN/160), using NDF files and the HDS files they are a special case of (SUN/33 and SUN/92 respectively), and reading and writing FITS files (SUN/136).
You can convert between different data formats using the CONVERT package, documented in SUN/55. CONVERT is extremely easy to use, and converting a FITS file, say, to an NDF is as easy as
fits2ndf myfile.fits myfile
If you have to read or write FITS files, then visit the
FITS home
page for the FITS users guide and the cfitsio
library. Although FITS files have a very simple format,
there are enough ways of getting things wrong that you
will, as usual, save yourself time in the long run by
taking the trouble to use the cfitsio
library. It's easier than you might think: the Quick
Start Guide contains most of what you'll ever need to
know. Note that, although the library is called
cfitsio, it's designed to be used with Fortran as
well, and the programmer's reference guide comes in two
flavours.
Once the data is there, you will need to visualise it. See Section 3.3 for some pointers to suitable software.