The following listing shows an example of how to use the FITSIO routines in a Fortran program. Refer to the cookbook.f program that is included with the FITSIO distribution for examples of other FITS programs.
program writeimage C Create a FITS primary array containing a 2-D image integer status,unit,blocksize,bitpix,naxis,naxes(2) integer i,j,group,fpixel,nelements,array(300,200) character filename*80 logical simple,extend status=0 C Name of the FITS file to be created: filename='ATESTFILE.FITS' C Get an unused Logical Unit Number to use to create the FITS file call ftgiou(unit,status) C create the new empty FITS file blocksize=1 call ftinit(unit,filename,blocksize,status) C initialize parameters about the FITS image (300 x 200 16-bit integers) simple=.true. bitpix=16 naxis=2 naxes(1)=300 naxes(2)=200 extend=.true. C write the required header keywords call ftphpr(unit,simple,bitpix,naxis,naxes,0,1,extend,status) C initialize the values in the image with a linear ramp function do j=1,naxes(2) do i=1,naxes(1) array(i,j)=i+j end do end do C write the array to the FITS file group=1 fpixel=1 nelements=naxes(1)*naxes(2) call ftpprj(unit,group,fpixel,nelements,array,status) C write another optional keyword to the header call ftpkyj(unit,'EXPOSURE',1500,'Total Exposure Time',status) C close the file and free the unit number call ftclos(unit, status) call ftfiou(unit, status) end