Procedure

     CKHAVE ( CK --- Are there any loaded? )

     ENTRY CKHAVE ( FOUND )

Abstract

     Determine whether or not any C-kernels are currently loaded.

Required_Reading

     CK
     DAF

Keywords

     CK

Declarations

    LOGICAL               FOUND

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     FOUND      O   .TRUE. if at least one C-kernel is loaded.

Detailed_Input

     None.

Detailed_Output

     FOUND    is returned with the value .TRUE. if at least one
              C-kernel is currently loaded. Otherwise it returns
              the value .FALSE.

Parameters

     None.

Exceptions

     Error free.

Files

     None.

Particulars

     This entry point allows the user to query the set of "loaded"
     C-kernels to make sure that at least one C-kernel has been loaded.
     This allows you to avoid making a search of an empty set of
     loaded kernels which forces a SPICELIB error to be signaled.

Examples

     The numerical results shown for this example may differ across
     platforms. The results depend on the SPICE kernels used as
     input, the compiler and supporting libraries, and the machine
     specific arithmetic implementation.

     1) Suppose you want to call one of the C-kernel readers, but wish
        to handle the exceptional case of "no kernels loaded" so that
        the SPICE exception handling mechanism is avoided in the case
        of an empty set of loaded kernels. The code example below
        shows how you might do this.


        Example code begins here.


              PROGRAM CKHAVE_EX1
              IMPLICIT NONE

        C
        C     Local variables.
        C
              LOGICAL               LOADED

        C
        C     We have not loaded any CK.
        C
              CALL CKHAVE ( LOADED )

              IF ( LOADED ) THEN

        C
        C        Here we could be calling CK readers. For this
        C        example, just display a message indicating that
        C        at least one CK has been loaded.
        C
                 WRITE(*,*) 'At least one CK has been loaded. '
             .          //  'You may call CK readers.'

              ELSE

                 WRITE(*,*) 'No CK has been loaded.'
                 WRITE(*,*) 'Calling CK readers will result in an '
             .          //  'error.'

              END IF

              END


        When this program was executed on a Mac/Intel/gfortran/64-bit
        platform, the output was:


         No CK has been loaded.
         Calling CK readers will result in an error.

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     B.V. Semenov       (JPL)
     W.L. Taber         (JPL)

Version

    SPICELIB Version 4.0.4, 16-JUL-2020 (JDR)

        Edited the header to comply with NAIF standard. Added complete
        code example based on existing example code fragment.

    SPICELIB Version 4.0.3, 30-JAN-2017 (NJB)

        Corrected various spelling errors within comments.

    SPICELIB Version 4.0.2, 28-FEB-2008 (BVS)

        Corrected the contents of the $Required_Reading section.

    SPICELIB Version 4.0.1, 31-OCT-2001 (NJB)

        Typo corrected.

    SPICELIB Version 4.0.0, 17-FEB-2000 (WLT)

        Added the Entry point CKHAVE.

    SPICELIB Version 3.0.0, 03-MAR-1999 (WLT)