gfstep_c

Index Page gfstep_c
A B C D E F G H I J K L M N O P Q R S T U V W X
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
       void gfstep_c ( SpiceDouble    time,
                       SpiceDouble  * step )
#### Abstract
       Return the time step set by the most recent call to gfsstp_c.
#### Required_Reading
       GF
       TIME
#### Keywords
       GEOMETRY
       SEARCH
       UTILITY
#### Brief_I/O
       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       time       I   Ignored ET value.
       step       O   Time step to take.
#### Detailed_Input
       time     is an ignored double precision number. This argument
                is present so the argument list of this routine is
                compatible with the GF step size routine argument list
                specification.

                When this routine is called from within the GF
                root-finding system, either the initial ET value of the
                current interval of the confinement window, or the
                value resulting from the last search step, is passed in
                via the `time' argument.
#### Detailed_Output
       step     is the output step size. This is the value set by the
                most recent call to gfsstp_c. Units are TDB seconds.

                `step' is used in the GF search root-bracketing process.
                `step' indicates how far to advance `time' so that `time' and
                time+step may bracket a state transition and definitely
                do not bracket more than one state transition.
#### Parameters
       None.
#### Exceptions
       1) If this routine is called before a step size has been
          set via a call to gfsstp_c, the error SPICE(NOTINITIALIZED)
          is signaled.
#### Files
       None.
#### Particulars
       This routine returns the time step set by the most recent call to
       gfsstp_c.
#### Examples
       1) User applications can pass gfstep_c to mid-level GF API routines
          expecting a step size routine as an input argument. For
          example, the GF API routine gfocce_c can be called as shown
          in the code fragment below.

                /.
                Select a twenty-second step. We'll ignore any occultations
                lasting less than 20 seconds.
                ./
                step = 20.0;
                gfsstp_c ( step );

                /.
                Perform the search.
                ./
                gfocce_c ( "ANY",
                           "MOON",     "ellipsoid",  "IAU_MOON",
                           "SUN",      "ellipsoid",  "IAU_SUN",
                           "LT",       "EARTH",      CNVTOL,
                           gfstep_c,   gfrefn_c,     rpt,
                           gfrepi_c,   gfrepu_c,     gfrepf_c,
                           bail,       gfbail_c,     cnfine,
                           &result                              );
#### Restrictions
       None.
#### Literature_References
       None.
#### Author_and_Institution
       N.J. Bachman   (JPL)
       L.S. Elson     (JPL)
       W.L. Taber     (JPL)
       I.M. Underwood (JPL)
       E.D. Wright    (JPL)
#### Version
       -CSPICE Version 1.0.0, 15-APR-2009 (LSE) (NJB)
#### Index_Entries
       GF get constant step size
#### Link to routine gfstep_c source file gfstep_c.c

    Thu Apr 16 08:58:16 2009