Procedure

     EKOPR ( EK, open file for reading )

     SUBROUTINE EKOPR ( FNAME, HANDLE )

Abstract

     Open an existing E-kernel file for reading.

Required_Reading

     EK

Keywords

     EK
     FILES
     UTILITY

Declarations

     IMPLICIT NONE

     CHARACTER*(*)         FNAME
     INTEGER               HANDLE

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     FNAME      I   Name of EK file.
     HANDLE     O   Handle attached to EK file.

Detailed_Input

     FNAME    is the name of an existing E-kernel file to be
              opened for read access.

Detailed_Output

     HANDLE   is the EK file handle of the file designated by
              FNAME. This handle is used to identify the file
              to other EK routines.

Parameters

     FTSIZE   is the maximum number of DAS files that a user can
              have open simultaneously. This includes any files used
              by the DAS system.

              See the include file das.inc for the actual value of
              this parameter.

Exceptions

     1)  If the indicated file cannot be opened, an error is signaled
         by a routine in the call tree of this routine.

     2)  If the indicated file has the wrong architecture version, an
         error is signaled by a routine in the call tree of this
         routine.

     3)  If an I/O error occurs while reading the indicated file, the
         error is signaled by a routine in the call tree of this
         routine.

Files

     See the EK Required Reading ek.req for a discussion of the EK file
     format.

Particulars

     This routine should be used to open an EK file for read access.
     EKs opened for read access may not be modified.

     Opening an EK file with this routine makes the EK accessible to
     the SPICELIB EK readers

        EKRCEC
        EKRCED
        EKRCEI

     all of which expect an EK file handle as an input argument. These
     readers allow a caller to read individual EK column entries.

     To make an EK available to the EK query system, the file must be
     loaded via EKLEF, rather than by this routine. See the EK
     Required Reading for further information.

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) Open an EK for read access and find the number of segments in
        it.

        Use the EK kernel below as test input file for loading the
        experiment database. This kernel contains the Deep
        Impact spacecraft sequence data based on the integrated
        Predicted Events File covering the whole primary mission,
        split into two segments.

           dif_seq_050112_050729.bes


        Example code begins here.


              PROGRAM EKOPR_EX1
              IMPLICIT NONE

        C
        C     SPICELIB functions
        C
              INTEGER               EKNSEG

        C
        C     Local variables.
        C
              INTEGER               HANDLE
              INTEGER               NSEG

        C
        C     Open the EK file, returning the file handle
        C     associated with the open file to the variable named
        C     HANDLE.
        C
              CALL EKOPR ( 'dif_seq_050112_050729.bes', HANDLE )


        C
        C     Return the number of segments in the EK.
        C
              NSEG = EKNSEG( HANDLE )
              WRITE(*,'(A,I3)') 'Number of segments =', NSEG

        C
        C     Close the file.
        C
              CALL EKCLS ( HANDLE )

              END


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


        Number of segments =  2

Restrictions

     1)  No more than FTSIZE DAS files may be opened simultaneously.
         See the include file das.inc for the value of FTSIZE.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)

Version

    SPICELIB Version 1.1.0, 06-JUL-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard. Added complete
        code example and updated $Parameters section.

        Corrected $Exceptions #1: this routine does not delete the
        input file if the file cannot be opened.

    SPICELIB Version 1.0.0, 26-AUG-1995 (NJB)