Procedure

     PCKR02 ( PCK, read record from type 2 segment )

     SUBROUTINE PCKR02 ( HANDLE, DESCR, ET, RECORD )

Abstract

     Read a single PCK data record from a segment of type 2
     (Chebyshev, 3-vector only).

Required_Reading

     PCK

Keywords

     EPHEMERIS

Declarations

     IMPLICIT NONE

     INTEGER               HANDLE
     DOUBLE PRECISION      DESCR    ( 5 )
     DOUBLE PRECISION      ET
     DOUBLE PRECISION      RECORD   ( * )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     HANDLE     I   File handle.
     DESCR      I   Segment descriptor.
     ET         I   Target epoch.
     RECORD     O   Data record.

Detailed_Input

     HANDLE,
     DESCR    are the file handle and segment descriptor for
              a PCK segment of type 2.

     ET       is a target epoch, for which a data record from
              a specific segment is required.

Detailed_Output

     RECORD   is the record from the specified segment which,
              when evaluated at epoch ET, will give the Euler
              angles (orientation) of some body.

Parameters

     None.

Exceptions

     None.

Files

     See argument HANDLE.

Particulars

     See the PCK Required Reading file for a description of the
     structure of a data type 2 (Chebyshev polynomials, Euler
     angles only) segment.

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) Dump the record of a type 2 PCK which, when evaluated at
        a given epoch, will give the Euler angles (orientation) of
        the Moon body-fixed frame with class ID 31004 with respect
        to J2000.

        Note that the data returned is in its rawest form, taken
        directly from the segment. As such, it will be meaningless to
        a user unless he/she understands the structure of the data
        type completely. Given that understanding, however, the PCKR02
        routine might be used to "dump" and check segment data for a
        particular epoch.

        Use the PCK kernel below to obtain the record.

           moon_pa_de418_1950-2050.bpc


        Example code begins here.


              PROGRAM PCKR02_EX1
              IMPLICIT NONE

        C
        C     Local parameters
        C
              INTEGER               BODY
              PARAMETER           ( BODY   = 31004 )

              INTEGER               DESCSZ
              PARAMETER           ( DESCSZ = 5     )

              INTEGER               IDSIZE
              PARAMETER           ( IDSIZE = 40    )

        C
        C     Set the maximum record size:
        C
        C        RSIZE = 2 + 3 * (PDEG +1)
        C
        C     Assume a maximum polynomial degree of 25, and
        C     knowing that PCKR02 returns RSIZE as first element
        C     of the output record...
        C
              INTEGER               RECRSZ
              PARAMETER           ( RECRSZ = 81    )

        C
        C     Local variables
        C
              CHARACTER*(IDSIZE)    SEGID

              DOUBLE PRECISION      BEGET
              DOUBLE PRECISION      DESCR  ( DESCSZ )
              DOUBLE PRECISION      ENDET
              DOUBLE PRECISION      ET
              DOUBLE PRECISION      RECORD ( RECRSZ )

              INTEGER               BADDR
              INTEGER               BODYID
              INTEGER               EADDR
              INTEGER               FRAMID
              INTEGER               HANDLE
              INTEGER               I
              INTEGER               INDEX
              INTEGER               PCKHDL
              INTEGER               PCKTYP
              INTEGER               PDEG
              INTEGER               RSIZE

              LOGICAL               FOUND

        C
        C     Load the PCK file.
        C
              CALL PCKLOF ( 'moon_pa_de418_1950-2050.bpc', PCKHDL )

        C
        C     Set the epoch. Use ephemeris time of J2000 epoch.
        C
              ET = 0.D0

        C
        C     Get a segment applicable to a specified body and epoch.
        C
              CALL PCKSFS ( BODY, ET, HANDLE, DESCR, SEGID, FOUND )

              IF ( FOUND ) THEN

        C
        C        Unpack the segment.
        C
                 CALL PCKUDS ( DESCR, BODYID, FRAMID, PCKTYP,
             .                 BEGET, ENDET,  BADDR,  EADDR  )


                 IF ( PCKTYP .EQ. 2 ) THEN

                    CALL PCKR02 ( HANDLE, DESCR, ET, RECORD )

                    RSIZE = RECORD(1)
                    PDEG  = ( RSIZE - 2 ) / 3 - 1

        C
        C           Output the data.
        C
                    WRITE(*,*) 'Record size      : ', RSIZE
                    WRITE(*,*) 'Polynomial degree: ', PDEG

                    WRITE(*,*) 'Record data      :'
                    WRITE(*,*) '   Interval midpoint: ', RECORD(2)
                    WRITE(*,*) '   Interval radius  : ', RECORD(3)

                    INDEX = 4
                    WRITE(*,*) '   RA coefficients  : '
                    DO I = 0, PDEG
                       WRITE(*,*) '      ', RECORD(INDEX+I)
                    END DO

                    INDEX = 4 + ( PDEG + 1 )
                    WRITE(*,*) '   DEC coefficients : '
                    DO I = 0, PDEG
                       WRITE(*,*) '      ', RECORD(INDEX+I)
                    END DO

                    INDEX = 4 + 2 * ( PDEG + 1 )
                    WRITE(*,*) '   W coefficients   : '
                    DO I = 0, PDEG
                       WRITE(*,*) '      ', RECORD(INDEX+I)
                    END DO

                 ELSE

                    WRITE(*,*) 'PCK is not type 2'

                 END IF

              ELSE

                 WRITE(*,*) '   ***** SEGMENT NOT FOUND *****'

              END IF

        C
        C     Unload the PCK file.
        C
              CALL PCKUOF ( PCKHDL )

              END


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


         Record size      :           32
         Polynomial degree:            9
         Record data      :
            Interval midpoint:    302400.00000000000
            Interval radius  :    345600.00000000000
            RA coefficients  :
                 -5.4242086033301107E-002
                 -5.2241405162792561E-005
                  8.9751456289930307E-005
                 -1.5288696963234620E-005
                  1.3218870864581395E-006
                  5.9822156790328180E-007
                 -6.5967702052551211E-008
                 -9.9084309118396298E-009
                  4.9276055963541578E-010
                  1.1612267413829385E-010
            DEC coefficients :
                 0.42498898565916610
                  1.3999219324235620E-004
                 -1.8855140511098865E-005
                 -2.1964684808526649E-006
                  1.4229817868138752E-006
                 -1.6991716166847001E-007
                 -3.4824688140649506E-008
                  2.9208428745895990E-009
                  4.4217757657060300E-010
                 -3.9211207055305402E-012
            W coefficients   :
                  2565.0633504619473
                 0.92003769451305328
                 -8.0503797901914501E-005
                  1.1960860244433900E-005
                 -1.2237900518372542E-006
                 -5.3651349407824562E-007
                  6.0843372260403005E-008
                  9.0211287487688797E-009
                 -4.6460429330339309E-010
                 -1.0446918704281774E-010

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     J. Diaz del Rio    (ODC Space)
     E.D. Wright        (JPL)
     K.S. Zukor         (JPL)

Version

    SPICELIB Version 1.1.2, 06-JUL-2021 (JDR)

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

    SPICELIB Version 1.1.1, 03-JAN-2014 (EDW)

        Minor edits to $Procedure; clean trailing whitespace.

    SPICELIB Version 1.1.0, 07-SEP-2001 (EDW)

        Replaced DAFRDA call with DAFGDA.
        Added IMPLICIT NONE.

    SPICELIB Version 1.0.0, 11-MAR-1993 (KSZ)