Special functions may be used with the command COMPUTE/KEYWORD. The currently supported functions are listed in the following table (on the next page). Note, that arg1, arg2 may either be the name of a keyword, the contents of which are used, or a constant. Character constants have to be enclosed in double quotes to distinguish them from a keyword name. On--line help for these functions is available via HELP COMPUTE/KEYWORD.
Table: Special Functions available for operations on keywords
As an example we want to to display the header of a FITS file stored on disk
(without converting the data), the FITS file name may be entered with or
without the file extension .mt;
if not given we append the type inside the procedure:
!+
! Example 16, MIDAS procedure exa16.prg
!+
DEFINE/PARAM P1 ? ? "Enter FITS file name:"
!
DEFINE/LOCAL INA/C/1/80 " " all ! that fills all elements of INA with blanks
DEFINE/LOCAL K/I/1/2 0,0
!
K = M$INDEX(P1,".mt") ! test, if type of FITS file entered
IF K .LT. 2 THEN
WRITE/KEYW INA P1.mt ! if not, append type
ELSE
WRITE/KEYW INA P1 ! if yes, no need to append type
ENDIF
INTAPE/FITS 1 midd ina fnn | $more
The MIDAS commands @@ exa16 test as well as @@ exa16 test.mt
will both display the header of the FITS file test.mt.
Note, that this procedure will display the header in a user friendly way, i.e.
one screen at a time (and only work for Unix).
One of the MIDAS verification procedures, verify3.prg
shows the usage of all currently available
functions. Enter @ vericopy to copy this procedure into your current
directory (also the usage of verify3 will be shown then).