Procedure

     GFSTEP ( GF, step size )

     SUBROUTINE GFSTEP ( TIME, STEP )

Abstract

     Return the time step set by the most recent call to GFSSTP.

Required_Reading

     GF
     TIME

Keywords

     GEOMETRY
     SEARCH
     UTILITY

Declarations

     IMPLICIT NONE

     DOUBLE PRECISION      TIME
     DOUBLE PRECISION      STEP

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. 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, the error SPICE(NOTINITIALIZED)
         is signaled.

Files

     None.

Particulars

     This routine returns the time step set by the most recent call to
     GFSSTP.

Examples

     1) In normal usage of a high-level GF API routine, the caller
        will pass in a constant step size STEP. The API routine will
        then make the call

           CALL GFSSTP ( STEP )

        Subsequent calls to GFSTEP during the search process conducted
        by the API routine will return STEP.


     2) User applications can pass GFSTEP to mid-level GF API routines
        expecting a step size routine as an input argument. For
        example, the GF API routine GFOCCE can be called as follows:


           Set the step size.

           CALL GFSSTP ( STEP )


           Look for solutions. (GFSTEP is the 11th argument.)

           CALL GFOCCE ( OCCTYP,  FRONT,   FSHAPE,  FFRAME,
          .              BACK,    BSHAPE,  BFRAME,  ABCORR,
          .              OBSRVR,  CNVTOL,  GFSTEP,  GFREFN,
          .              RPT,     GFREPI,  GFREPU,  GFREPF,
          .              BAIL,    GFBAIL,  CNFINE,  RESULT )

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     L.S. Elson         (JPL)
     W.L. Taber         (JPL)
     I.M. Underwood     (JPL)
     E.D. Wright        (JPL)

Version

    SPICELIB Version 1.1.1, 03-JUN-2021 (JDR)

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.1.0, 31-AUG-2010 (EDW)

        Expanded error message on STEP for clarity.

        Added TIME = TIME declaration to eliminate unused dummy
        variable warning during compilation.

    SPICELIB Version 1.0.0, 05-MAR-2009 (NJB) (LSE) (IMU) (WLT) (EDW)