cknr02 |
Table of contents
ProcedureCKNR02 ( C-kernel, number of records, type 02 ) SUBROUTINE CKNR02 ( HANDLE, DESCR, NREC ) AbstractReturn the number of pointing records in a CK type 02 segment. The segment is identified by a CK file handle and segment descriptor. Required_ReadingCK DAF KeywordsPOINTING DeclarationsIMPLICIT NONE INTEGER HANDLE DOUBLE PRECISION DESCR ( * ) INTEGER NREC Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- HANDLE I The handle of the CK file containing the segment. DESCR I The descriptor of the type 2 segment. NREC O The number of records in the segment. Detailed_InputHANDLE is the handle of the binary CK file containing the segment. The file should have been opened for read or write access, by CKLPF, DAFOPR or DAFOPW. DESCR is the packed descriptor of a data type 2 CK segment. Detailed_OutputNREC is the number of pointing records in the type 2 segment associated with HANDLE and DESCR. ParametersNone. Exceptions1) If the segment indicated by DESCR is not a type 2 segment, the error SPICE(CKWRONGDATATYPE) is signaled. 2) If the specified handle does not belong to any file that is currently known to be open, an error is signaled by a routine in the call tree of this routine. 3) If DESCR is not a valid descriptor of a segment in the CK file specified by HANDLE, the results of this routine are unpredictable. FilesThe CK file specified by HANDLE should be open for read or write access. ParticularsFor a complete description of the internal structure of a type 2 segment, see the CK required reading. This routine returns the number of pointing records contained in the specified segment. It is normally used in conjunction with CKGR02, which returns the Ith record in the segment. ExamplesThe 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) The following code example extracts the start and end SCLK time, seconds per tick rate, platform's +Z axis direction, and angular velocity vector for each pointing instance in the first segment in a CK file that contains segments of data type 2. Use the CK kernel below, available in the Viking Orbiter PDS archives, as input for the code example. vo2_swu_ck2.bc Example code begins here. PROGRAM CKNR02_EX1 IMPLICIT NONE DOUBLE PRECISION AV ( 3 ) DOUBLE PRECISION CMAT ( 3, 3 ) DOUBLE PRECISION DCD ( 2 ) DOUBLE PRECISION DESCR ( 5 ) DOUBLE PRECISION QUAT ( 4 ) DOUBLE PRECISION RECORD ( 10 ) DOUBLE PRECISION SCLKE DOUBLE PRECISION SCLKR DOUBLE PRECISION SCLKS DOUBLE PRECISION Z ( 3 ) INTEGER ICD ( 6 ) INTEGER HANDLE INTEGER NREC INTEGER I LOGICAL FOUND C C First load the file. (The file may also be opened by C using CKLPF). C CALL DAFOPR ( 'vo2_swu_ck2.bc', HANDLE ) C C Begin forward search. Find the first array. C CALL DAFBFS ( HANDLE ) CALL DAFFNA ( FOUND ) C C Get segment descriptor. C CALL DAFGS ( DESCR ) C C Unpack the segment descriptor into its double precision C and integer components. C CALL DAFUS ( DESCR, 2, 6, DCD, ICD ) C C The data type for a segment is located in the third C integer component of the descriptor. C IF ( ICD( 3 ) .EQ. 2 ) THEN C C How many records does this segment contain? C CALL CKNR02 ( HANDLE, DESCR, NREC ) DO I = 1, NREC C C Get the Ith record in the segment. C CALL CKGR02 ( HANDLE, DESCR, I, RECORD ) C C Unpack RECORD into the start and end time, rate in C TDB seconds/tick, quaternion, and av. C SCLKS = RECORD ( 1 ) SCLKE = RECORD ( 2 ) SCLKR = RECORD ( 3 ) CALL MOVED ( RECORD(4), 4, QUAT ) CALL MOVED ( RECORD(8), 3, AV ) C C The +Z axis direction is the third row of the C C-matrix. C CALL Q2M ( QUAT, CMAT ) Z(1) = CMAT(3,1) Z(2) = CMAT(3,2) Z(3) = CMAT(3,3) C C Write out the results. C WRITE (*,'(A,I2)') 'Record: ', I WRITE (*,'(A,F21.6)') ' Start encoded SCLK:', . SCLKS WRITE (*,'(A,F21.6)') ' End encoded SCLK :', . SCLKE WRITE (*,'(A,F21.6)') ' TDB Seconds/tick :', . SCLKR WRITE (*,'(A,3F13.8)') ' +Z axis :', . Z WRITE (*,'(A,3F13.8)') ' Angular velocity :', . AV WRITE (*,*) END DO END IF END When this program was executed on a Mac/Intel/gfortran/64-bit platform, the output was: Record: 1 Start encoded SCLK: 32380393707.000015 End encoded SCLK : 32380395707.000015 TDB Seconds/tick : 0.001000 +Z axis : 0.62277152 -0.29420673 0.72498141 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 2 Start encoded SCLK: 32380402605.999947 End encoded SCLK : 32380404605.999947 TDB Seconds/tick : 0.001000 +Z axis : 0.62172600 -0.27894910 0.73187716 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 3 Start encoded SCLK: 32380412542.000053 End encoded SCLK : 32380414542.000053 TDB Seconds/tick : 0.001000 +Z axis : 0.62183610 -0.26307233 0.73764003 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 4 Start encoded SCLK: 32827264875.000000 End encoded SCLK : 32827266875.000000 TDB Seconds/tick : 0.001000 +Z axis : 0.82984105 -0.44796078 0.33270853 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 5 Start encoded SCLK: 32827403805.999992 End encoded SCLK : 32827405805.999992 TDB Seconds/tick : 0.001000 +Z axis : 0.80812500 -0.44911178 0.38109395 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 6 Start encoded SCLK: 32827412705.000042 End encoded SCLK : 32827414705.000042 TDB Seconds/tick : 0.001000 +Z axis : 0.81120505 -0.43593555 0.38975193 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 7 Start encoded SCLK: 32827417284.000038 End encoded SCLK : 32827419284.000038 TDB Seconds/tick : 0.001000 +Z axis : 0.81313834 -0.42861613 0.39382008 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 8 Start encoded SCLK: 33793314593.000053 End encoded SCLK : 33793316593.000053 TDB Seconds/tick : 0.001000 +Z axis : 0.79860617 -0.37840751 0.46801275 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 9 Start encoded SCLK: 33793332478.000046 End encoded SCLK : 33793334478.000046 TDB Seconds/tick : 0.001000 +Z axis : 0.77861783 -0.39171670 0.49021658 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 10 Start encoded SCLK: 33793341463.000061 End encoded SCLK : 33793343463.000061 TDB Seconds/tick : 0.001000 +Z axis : 0.76852381 -0.39797437 0.50098659 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 11 Start encoded SCLK: 33793350363.000034 End encoded SCLK : 33793352363.000034 TDB Seconds/tick : 0.001000 +Z axis : 0.75779934 -0.40484364 0.51170478 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 12 Start encoded SCLK: 33984028250.000000 End encoded SCLK : 33984030250.000000 TDB Seconds/tick : 0.001000 +Z axis : 0.77099184 -0.39926339 0.49614546 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 13 Start encoded SCLK: 33984046134.999992 End encoded SCLK : 33984048134.999992 TDB Seconds/tick : 0.001000 +Z axis : 0.75024440 -0.41218993 0.51694564 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 14 Start encoded SCLK: 33984055121.000053 End encoded SCLK : 33984057121.000053 TDB Seconds/tick : 0.001000 +Z axis : 0.73947359 -0.41886863 0.52699894 Angular velocity : 0.00000000 0.00000000 0.00000000 Record: 15 Start encoded SCLK: 33984220835.999966 [...] Warning: incomplete output. Only 100 out of 875 lines have been provided. Restrictions1) The binary CK file containing the segment whose descriptor was passed to this routine must be opened for read or write access by CKLPF, DAFOPR or DAFOPW. Literature_ReferencesNone. Author_and_InstitutionJ. Diaz del Rio (ODC Space) J.M. Lynch (JPL) VersionSPICELIB Version 1.1.0, 26-OCT-2021 (JDR) Added IMPLICIT NONE statement. Edited the header to comply with NAIF standard. Created complete code example from existing code fragment. Improved text in the $Abstract section. SPICELIB Version 1.0.0, 25-NOV-1992 (JML) |
Fri Dec 31 18:36:03 2021