Index of Functions: A B C D E F G H I J K L M N O P Q R S T U V W X
Index Page gfudb_c
Table of contents
Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries
#### Procedure
       gfudb_c ( GF, user defined boolean )

       void gfudb_c (  void            ( * udfuns ) ( SpiceDouble       et,
                                                      SpiceDouble     * value ),

                       void            ( * udfunb ) ( void ( * udfuns )
                                                           ( SpiceDouble   et,
                                                             SpiceDouble * value ),

                                                      SpiceDouble       et,
                                                      SpiceBoolean    * xbool ),

                       SpiceDouble          step,
                       SpiceCell          * cnfine,
                       SpiceCell          * result )
#### Abstract
       Perform a GF search on a user defined boolean quantity.
#### Required_Reading
       GF
       WINDOWS
#### Keywords
       EVENT
       GEOMETRY
       SEARCH
       WINDOW
#### Brief_I/O
       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       SPICE_GF_CNVTOL
                  P   Convergence tolerance.
       udfuns     I   Name of the routine that computes a scalar
                      quantity corresponding to an `et'.
       udfunb     I   Name of the routine returning the boolean value
                      corresponding to an `et'.
       step       I   Constant step size in seconds for finding geometric
                      events.
       cnfine    I-O  SPICE window to which the search is restricted.
       result     O   SPICE window containing results.
#### Detailed_Input
       udfuns      is the routine that returns the value of the scalar
                   quantity of interest at time `et'. The prototype of
                   `udfuns' is:

                      void   ( * udfuns ) ( SpiceDouble       et,
                                            SpiceDouble     * value )

                   where:

                      et      a double precision value representing
                              ephemeris time, expressed as seconds past
                              J2000 TDB at which to evaluate `udfuns'.

                      value   is the value of the scalar quantity
                              at `et'.

       udfunb      is the user defined routine returning a boolean value for
                   an epoch `et'. The prototype of `udfunb' is:

                     void    ( * udfunb ) ( void          ( * udfuns )
                                                        ( SpiceDouble   et,
                                                          SpiceDouble * value ),
                                            SpiceDouble       et,
                                            SpiceBoolean    * xbool )

                   where:

                      udfuns   the name of the scalar function as
                               defined above.

                      et       a double precision value representing
                               ephemeris time, expressed as seconds past
                               J2000 TDB, at which to evaluate `udfunb'.

                      xbool     the boolean value at `et'.

                   gfudb_c will correctly operate only for boolean functions
                   with true conditions defining non zero measure time
                   intervals.

                   Note, `udfunb' need not call `udfuns'. The use of `udfuns' is
                   determined by the needs of the calculation and the user's
                   design.

       step        is the step size to be used in the search. `step' must be
                   shorter than any interval, within the confinement window,
                   over which the user defined boolean function is met. In
                   other words, `step' must be shorter than the shortest time
                   interval for which the boolean function is true; `step'
                   must also be shorter than the shortest time interval
                   between two boolean function true events occurring within
                   the confinement window (see below). However, `step' must
                   not be *too* short, or the search will take an
                   unreasonable amount of time.

                   The choice of `step' affects the completeness but not
                   the precision of solutions found by this routine; the
                   precision is controlled by the convergence tolerance.
                   See the discussion of the parameter SPICE_GF_CNVTOL for
                   details.

                   `step' has units of TDB seconds.

       cnfine      is a SPICE window that confines the time period over
                   which the specified search is conducted. `cnfine' may
                   consist of a single interval or a collection of
                   intervals.

                   In some cases the confinement window can be used to
                   greatly reduce the time period that must be searched
                   for the desired solution. See the -Particulars section
                   below for further discussion.

                   See the -Examples section below for a code example
                   that shows how to create a confinement window.

                   In some cases the observer's state may be computed at
                   times outside of `cnfine' by as much as 2 seconds. See
                   -Particulars for details.

                   `cnfine' must be declared as a double precision SpiceCell.

                   CSPICE provides the following macro, which declares and
                   initializes the cell

                      SPICEDOUBLE_CELL        ( cnfine, CNFINESZ );

                   where CNFINESZ is the maximum capacity of `cnfine'.
#### Detailed_Output
       cnfine      is the input confinement window, updated if necessary so the
                   control area of its data array indicates the window's size
                   and cardinality. The window data are unchanged.

       result      is a SPICE window containing the time intervals within
                   the confinement window, during which the specified
                   boolean quantity is SPICETRUE.

                   `result' must be declared and initialized with sufficient
                   size to capture the full set of time intervals within the
                   search region on which the specified condition is satisfied.

                   If `result' is non-empty on input, its contents will be
                   discarded before gfudb_c conducts its search.

                   The endpoints of the time intervals comprising `result' are
                   interpreted as seconds past J2000 TDB.

                   If no times within the confinement window satisfy the
                   search criteria, `result' will be returned with a
                   cardinality of zero.

                   `result' must be declared as a double precision SpiceCell.

                   CSPICE provides the following macro, which declares and
                   initializes the cell

                      SPICEDOUBLE_CELL        ( result, RESULTSZ );

                   where RESULTSZ is the maximum capacity of `result'.
#### Parameters
       SPICE_GF_CNVTOL

                   is the convergence tolerance used for finding endpoints
                   of the intervals comprising the result window.
                   SPICE_GF_CNVTOL is used to determine when binary
                   searches for roots should terminate: when a root is
                   bracketed within an interval of length SPICE_GF_CNVTOL,
                   the root is considered to have been found.

                   The accuracy, as opposed to precision, of roots found by
                   this routine depends on the accuracy of the input data.
                   In most cases, the accuracy of solutions will be
                   inferior to their precision.

                   SPICE_GF_CNVTOL is declared in the header file
                   SpiceGF.h.
#### Exceptions
       1)  In order for this routine to produce correct results,
           the step size must be appropriate for the problem at hand.
           Step sizes that are too large may cause this routine to miss
           roots; step sizes that are too small may cause this routine
           to run unacceptably slowly and in some cases, find spurious
           roots.

           This routine does not diagnose invalid step sizes, except that
           if the step size is non-positive, an error is signaled by a
           routine in the call tree of this routine.

       2)  Due to numerical errors, in particular,

              - truncation error in time values
              - finite tolerance value
              - errors in computed geometric quantities

           it is *normal* for the condition of interest to not always be
           satisfied near the endpoints of the intervals comprising the
           `result' window. One technique to handle such a situation,
           slightly contract `result' using the window routine wncond_c.

       3)  If an error (typically cell overflow) occurs while performing
           window arithmetic, the error is signaled by a routine
           in the call tree of this routine.

       4)  If the size of the SPICE window `result' is less than 2 or not
           an even value, the error SPICE(INVALIDDIMENSION) is signaled
           by a routine in the call tree of this routine.

       5)  If `result' has insufficient capacity to contain the number of
           intervals on which the specified condition is met, an error is
           signaled by a routine in the call tree of this routine.

       6)  If required ephemerides or other kernel data are not
           available, an error is signaled by a routine in the call tree
           of this routine.

       7)  If any the `cnfine' or `result' cell arguments has a type
           other than SpiceDouble, the error SPICE(TYPEMISMATCH) is
           signaled.
#### Files
       Appropriate kernels must be loaded by the calling program before
       this routine is called.

       If the boolean function requires access to ephemeris data:

       -  SPK data: ephemeris data for any body over the
          time period defined by the confinement window must be
          loaded. If aberration corrections are used, the states of
          target and observer relative to the solar system barycenter
          must be calculable from the available ephemeris data.
          Typically ephemeris data are made available by loading one
          or more SPK files via furnsh_c.

       -  If non-inertial reference frames are used, then PCK
          files, frame kernels, C-kernels, and SCLK kernels may be
          needed.

       -  Certain computations can expand the time window over which
          `udfuns' and `udfunb' require data; such data must be provided by
          loaded kernels. See -Particulars for details.

       In all cases, kernel data are normally loaded once per program
       run, NOT every time this routine is called.
#### Particulars
       This routine determines a set of one or more time intervals
       within the confinement window when the boolean function
       evaluates to true. The resulting set of intervals is returned
       as a SPICE window.

       Below we discuss in greater detail aspects of this routine's
       solution process that are relevant to correct and efficient
       use of this routine in user applications.

       udfuns Default Template
       =======================

       The boolean function includes an argument for an input scalar
       function. Use of a scalar function during the evaluation of
       the boolean function is not required. SPICE provides a no-op
       scalar routine, udf_c, as a dummy argument for instances when
       the boolean function does not need to call the scalar function.

       The Search Process
       ==================

       The search for boolean events is treated as a search for state
       transitions: times are sought when the boolean function value
       changes from true to false or vice versa.

       Step Size
       =========

       Each interval of the confinement window is searched as follows:
       first, the input step size is used to determine the time
       separation at which the boolean function will be sampled.
       Starting at the left endpoint of the interval, samples of the
       boolean function will be taken at each step. If a state change
       is detected, a root has been bracketed; at that point, the
       "root"--the time at which the state change occurs---is found by a
       refinement process, for example, via binary search.

       Note that the optimal choice of step size depends on the lengths
       of the intervals over which the boolean function is constant:
       the step size should be shorter than the shortest such interval
       and the shortest separation between the intervals, within
       the confinement window.

       Having some knowledge of the relative geometry of the targets and
       observer can be a valuable aid in picking a reasonable step size.
       In general, the user can compensate for lack of such knowledge by
       picking a very short step size; the cost is increased computation
       time.

       Note that the step size is not related to the precision with which
       the endpoints of the intervals of the result window are computed.
       That precision level is controlled by the convergence tolerance.

       Convergence Tolerance
       =====================

       Once a root has been bracketed, a refinement process is used to
       narrow down the time interval within which the root must lie.
       This refinement process terminates when the location of the root
       has been determined to within an error margin called the
       "convergence tolerance." The default convergence tolerance
       used by this routine is set by the parameter SPICE_GF_CNVTOL (defined
       in SpiceGF.h).

       The value of SPICE_GF_CNVTOL is set to a "tight" value so that the
       tolerance doesn't become the limiting factor in the accuracy of
       solutions found by this routine. In general the accuracy of input
       data will be the limiting factor.

       The user may change the convergence tolerance from the default
       SPICE_GF_CNVTOL value by calling the routine gfstol_c, e.g.

          gfstol_c ( tolerance value );

       Call gfstol_c prior to calling this routine. All subsequent
       searches will use the updated tolerance value.

       Setting the tolerance tighter than SPICE_GF_CNVTOL is unlikely to be
       useful, since the results are unlikely to be more accurate.
       Making the tolerance looser will speed up searches somewhat,
       since a few convergence steps will be omitted. However, in most
       cases, the step size is likely to have a much greater effect
       on processing time than would the convergence tolerance.

       The Confinement Window
       ======================

       The simplest use of the confinement window is to specify a time
       interval within which a solution is sought.

       The confinement window also can be used to restrict a search to
       a time window over which required data are known to be
       available.

       In some cases, the confinement window can be used to make
       searches more efficient. Sometimes it's possible to do an
       efficient search to reduce the size of the time period over
       which a relatively slow search of interest must be performed.
       See the "CASCADE" example program in gf.req for a demonstration.

       Certain user-defined computations may expand the window over
       which computations are performed. Here "expansion" of a window by
       an amount "T" means that the left endpoint of each interval
       comprising the window is shifted left by T, the right endpoint of
       each interval is shifted right by T, and any overlapping
       intervals are merged. Note that the input window `cnfine' itself is
       not modified.

       Computation of observer-target states by spkezr_c or spkez_c, using
       stellar aberration corrections, requires the state of the
       observer, relative to the solar system barycenter, to be computed
       at times offset from the input time by +/- 1 second. If the input
       time ET is used by `udfuns' or `udfunb' to compute such a state, the
       window over which the observer state is computed is expanded by 1
       second.

       When light time corrections are used in the computation of
       observer-target states, expansion of the search window also
       affects the set of times at which the light time-corrected states
       of the targets are computed.

       In addition to possible expansion of the search window when
       stellar aberration corrections are used, round-off error should
       be taken into account when the need for data availability is
       analyzed.
#### Examples
       The numerical results shown for these examples 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) Calculate the time intervals when the position of the moon relative
          to the earth in the IAU_EARTH frame has a positive value in for
          the Z position component, with also a positive value for the Vz
          velocity component.

          Use the meta-kernel shown below to load the required SPICE
          kernels.

             KPL/MK

             File name: gfudb_ex1.tm

             This meta-kernel is intended to support operation of SPICE
             example programs. The kernels shown here should not be
             assumed to contain adequate or correct versions of data
             required by SPICE-based user applications.

             In order for an application to use this meta-kernel, the
             kernels referenced here must be present in the user's
             current working directory.

             The names and contents of the kernels referenced
             by this meta-kernel are as follows:

                File name                     Contents
                ---------                     --------
                de418.bsp                     Planetary ephemeris
                pck00008.tpc                  Planet orientation and
                                              radii
                naif0009.tls                  Leapseconds

             \begindata

                KERNELS_TO_LOAD = ( 'de418.bsp',
                                    'pck00008.tpc',
                                    'naif0009.tls'  )

             \begintext

             End of meta-kernel

          Example code begins here.

          /.
             Program gfudb_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          #define       MAXWIN    20000
          #define       TIMFMT    "YYYY-MON-DD HR:MN:SC.###"
          #define       TIMLEN    41
          #define       NLOOPS    7

          void gfq ( void ( * udfunc ) ( SpiceDouble    et,
                                         SpiceDouble  * value ),
                     SpiceDouble et,
                     SpiceBoolean * xbool );

          int main( )
             {

             /.
             Create the needed windows. Note, one interval
             consists of two values, so the total number
             of cell values to allocate is twice
             the number of intervals.
             ./
             SPICEDOUBLE_CELL ( result, 2*MAXWIN );
             SPICEDOUBLE_CELL ( cnfine, 2        );

             SpiceDouble       begtim;
             SpiceDouble       endtim;
             SpiceDouble       left;
             SpiceDouble       right;
             SpiceDouble       step;
             SpiceDouble       lt;
             SpiceDouble       state  [6];

             SpiceChar         begstr [ TIMLEN ];
             SpiceChar         endstr [ TIMLEN ];

             SpiceInt          count;
             SpiceInt          i;

             /.
             Load kernels.
             ./
             furnsh_c( "gfudb_ex1.tm" );

             /.
             Store the time bounds of our search interval in the 'cnfine'
             confinement window.
             ./
             str2et_c ( "Jan 1 2011", &begtim );
             str2et_c ( "Apr 1 2011", &endtim );

             wninsd_c ( begtim, endtim, &cnfine );

             /.
             The moon orbit about the earth-moon barycenter is
             twenty-eight days. The event condition occurs
             during (very) approximately a quarter of the orbit. Use
             a step of five days.
             ./

             step = 5.0 * spd_c();

             gfudb_c ( udf_c,
                       gfq,
                       step,
                       &cnfine,
                       &result );

             count = wncard_c( &result );

             /.
             Display the results.
             ./
             if (count == 0 )
                {
                printf ( "Result window is empty.\n\n" );
                }
             else
                {
                for ( i = 0;  i < count;  i++ )
                   {

                   /.
                   Fetch the endpoints of the Ith interval
                   of the result window.
                   ./
                   wnfetd_c ( &result, i, &left, &right );

                   printf ( "Interval %d\n", (int)i );

                   timout_c ( left, TIMFMT, TIMLEN, begstr );
                   printf   ( "   Interval start: %s \n", begstr );
                   spkez_c  ( 301, left, "IAU_EARTH", "NONE", 399, state, &lt);
                   printf   ( "                Z= %.12g \n", state[2] );
                   printf   ( "               Vz= %.12g \n", state[5] );

                   timout_c ( right, TIMFMT, TIMLEN, endstr );
                   printf   ( "   Interval end  : %s \n", endstr );
                   spkez_c  ( 301, right, "IAU_EARTH", "NONE", 399, state, &lt);
                   printf   ( "                Z= %.12g \n",   state[2] );
                   printf   ( "               Vz= %.12g \n\n", state[5] );
                   }

                }

             kclear_c();
             return( 0 );
             }

          /.
          The user defined functions required by gfudb_c.

             udf_c   for udfuns
             gfq     for udfunb
          ./

          /.
          -Procedure Procedure gfq
          ./

          void gfq ( void ( * udfuns ) ( SpiceDouble    et,
                                         SpiceDouble  * value ),
                     SpiceDouble et,
                     SpiceBoolean * xbool )

          /.
          -Abstract

            User defined geometric boolean function:

               Z >= 0 with dZ/dt > 0.

          ./
             {

             /.
             Initialization. Retrieve the vector from the earth to
             the moon in the IAU_EARTH frame, without aberration
             correction.
             ./
             SpiceInt             targ   = 301;
             SpiceInt             obs    = 399;

             SpiceChar          * ref    = "IAU_EARTH";
             SpiceChar          * abcorr = "NONE";

             SpiceDouble          state [6];
             SpiceDouble          lt;

             /.
             Evaluate the state of TARG from OBS at ET with
             correction ABCORR.
             ./
             spkez_c ( targ, et, ref, abcorr, obs, state, &lt );

             /.
             Calculate the boolean value.
             ./

             *xbool = (state[2] >= 0.0) && (state[5] > 0.0);

             return;
             }

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

          Interval 0
             Interval start: 2011-JAN-09 15:24:23.416
                          Z= -1.12510406325e-07
                         Vz= 0.396984084546
             Interval end  : 2011-JAN-16 16:08:28.564
                          Z= 156247.488042
                         Vz= 4.0992339731e-13

          Interval 1
             Interval start: 2011-FEB-05 23:17:57.359
                          Z= -1.24675068491e-07
                         Vz= 0.396781282843
             Interval end  : 2011-FEB-13 01:38:28.426
                          Z= 157016.055001
                         Vz= 1.73745783386e-13

          Interval 2
             Interval start: 2011-MAR-05 06:08:17.668
                          Z= -7.77218360781e-08
                         Vz= 0.393990253634
             Interval end  : 2011-MAR-12 10:27:45.189
                          Z= 157503.773777
                         Vz= -2.97863513368e-13

       2) Calculate the time intervals when the Z component of the earth
          to moon position vector in the IAU_EARTH frame has value
          between -1000 km and 1000 km (e.g. above and below the equatorial
          plane).

          Use the meta-kernel from the first example.

          Example code begins here.

          /.
             Program gfudb_ex2
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          #define       MAXWIN    20000
          #define       TIMFMT    "YYYY-MON-DD HR:MN:SC.###"
          #define       TIMLEN    41
          #define       NLOOPS    7

          void gfq ( SpiceDouble    et,
                     SpiceDouble  * value );

          void gfb ( void ( * udfuns ) ( SpiceDouble    et,
                                         SpiceDouble  * value ),
                     SpiceDouble    et,
                     SpiceBoolean * xbool );

          int main( )
             {

             /.
             Create the needed windows. Note, one interval
             consists of two values, so the total number
             of cell values to allocate is twice
             the number of intervals.
             ./
             SPICEDOUBLE_CELL ( result, 2*MAXWIN );
             SPICEDOUBLE_CELL ( cnfine, 2        );

             SpiceDouble       begtim;
             SpiceDouble       endtim;
             SpiceDouble       left;
             SpiceDouble       right;
             SpiceDouble       step;
             SpiceDouble       lt;
             SpiceDouble       state  [6];

             SpiceChar         begstr [ TIMLEN ];
             SpiceChar         endstr [ TIMLEN ];

             SpiceInt          count;
             SpiceInt          i;

             /.
             Load kernels.
             ./
             furnsh_c( "gfudb_ex1.tm" );

             /.
             Store the time bounds of our search interval in the 'cnfine'
             confinement window.
             ./
             str2et_c ( "Jan 1 2011", &begtim );
             str2et_c ( "Apr 1 2011", &endtim );

             wninsd_c ( begtim, endtim, &cnfine );

             /.
             The duration of the event is approximately ninety minutes.
             Use a step of one hour.
             ./

             step = 60.*60.;

             gfudb_c ( gfq,
                       gfb,
                       step,
                       &cnfine,
                       &result );

             count = wncard_c( &result );

             /.
             Display the results.
             ./
             if (count == 0 )
                {
                printf ( "Result window is empty.\n\n" );
                }
             else
                {
                for ( i = 0;  i < count;  i++ )
                   {

                   /.
                   Fetch the endpoints of the Ith interval
                   of the result window.
                   ./
                   wnfetd_c ( &result, i, &left, &right );

                   printf ( "Interval %d\n", (int)i );

                   timout_c ( left, TIMFMT, TIMLEN, begstr );
                   printf   ( "   Interval start: %s \n", begstr );
                   spkez_c  ( 301, left, "IAU_EARTH", "NONE", 399, state, &lt);
                   printf   ( "                Z= %.12g \n", state[2] );

                   timout_c ( right, TIMFMT, TIMLEN, endstr );
                   printf   ( "   Interval end  : %s \n", endstr );
                   spkez_c  ( 301, right, "IAU_EARTH", "NONE", 399, state, &lt);
                   printf   ( "                Z= %.12g \n",   state[2] );
                   }

                }

             kclear_c();
             return( 0 );
             }

          /.
          The user defined functions required by gfudb_c.

             gfq     for udfuns
             gfb     for udfunb
          ./

          /.
          -Procedure Procedure gfq
          ./

          void gfq ( SpiceDouble    et,
                     SpiceDouble  * value )

          /.
          -Abstract

            User defined scalar function:

          ./
             {

             /.
             Initialization. Retrieve the vector from the earth to
             the moon in the IAU_EARTH frame, without aberration
             correction.
             ./
             SpiceInt             targ   = 301;
             SpiceInt             obs    = 399;

             SpiceChar          * ref    = "IAU_EARTH";
             SpiceChar          * abcorr = "NONE";

             SpiceDouble          pos [3];
             SpiceDouble          lt;

             /.
             Evaluate the state of TARG from OBS at ET with
             correction ABCORR.
             ./
             spkezp_c ( targ, et, ref, abcorr, obs, pos, &lt );

             *value = pos[2];

             return;
             }

          /.
          -Procedure Procedure gfb
          ./

          void gfb ( void ( * udfuns ) ( SpiceDouble    et,
                                         SpiceDouble  * value ),
                     SpiceDouble    et,
                     SpiceBoolean * xbool )

          /.
          -Abstract

            User defined boolean function:

          ./
             {
             SpiceDouble          value;
             SpiceDouble          lim1   = -1000.;
             SpiceDouble          lim2   = 1000.;

             udfuns( et, &value );

             /.
             Calculate the boolean value.
             ./

             *xbool = (value >= lim1) && (value <= lim2);

             return;
             }

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

          Interval 0
             Interval start: 2011-JAN-09 14:42:24.485
                          Z= -999.999999841
             Interval end  : 2011-JAN-09 16:06:22.503
                          Z= 999.999999876
          Interval 1
             Interval start: 2011-JAN-23 04:07:44.456
                          Z= 999.999999922
             Interval end  : 2011-JAN-23 05:23:06.244
                          Z= -1000.00000013
          Interval 2
             Interval start: 2011-FEB-05 22:35:57.157
                          Z= -1000.0000001
             Interval end  : 2011-FEB-05 23:59:57.749
                          Z= 999.999999843
          Interval 3
             Interval start: 2011-FEB-19 14:11:28.294
                          Z= 1000.0000001
             Interval end  : 2011-FEB-19 15:26:01.719
                          Z= -999.999999854
          Interval 4
             Interval start: 2011-MAR-05 05:25:59.562
                          Z= -1000.00000003
             Interval end  : 2011-MAR-05 06:50:35.862
                          Z= 1000.00000009
          Interval 5
             Interval start: 2011-MAR-19 01:30:19.166
                          Z= 999.99999983
             Interval end  : 2011-MAR-19 02:45:21.112
                          Z= -1000.00000001
#### Restrictions
       1)  Any kernel files required by this routine must be loaded
           before this routine is called.
#### Literature_References
       None.
#### Author_and_Institution
       N.J. Bachman        (JPL)
       J. Diaz del Rio     (ODC Space)
       E.D. Wright         (JPL)
#### Version
       -CSPICE Version 1.0.2, 03-NOV-2021 (JDR) (NJB)

           Updated header to describe use of expanded confinement window.

           Edited the header to comply with NAIF standard.

           Reduced the search interval to limit the length of the solutions.
           Removed "Compile date" printout and unnecessary include files in both
           examples.

           Updated the description of "cnfine" and "result" arguments.

       -CSPICE Version 1.0.1, 28-JUN-2016 (EDW)

           Edit to Example code, SpiceInts output as ints using
           explicit casting.

       -CSPICE Version 1.0.0, 23-OCT-2013 (EDW) (NJB)
#### Index_Entries
       GF user defined boolean function search
#### Link to routine gfudb_c source file gfudb_c.c

    Fri Dec 31 18:41:07 2021