Index Page uddc_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 uddc_c ( void            ( * udfunc ) ( SpiceDouble    x,
                                                    SpiceDouble  * value ),
                     SpiceDouble         x,
                     SpiceDouble         dx,
                     SpiceBoolean      * isdecr )
#### Abstract
       SPICE private routine intended solely for the support of SPICE
       routines. Users should not call this routine directly due to the
       volatile nature of this routine.

       This routine calculates the derivative of 'udfunc' with respect
       to time for 'et', then determines if the derivative has a
       negative value.
#### Required_Reading
       GF
#### Keywords
       DERIVATIVE
       GEOMETRY
#### Brief_I/O
       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------

       udfunc     I   The routine that computes the scalar value
                      of interest.
       x          I   Independent variable of 'udfunc'.
       dx         I   Interval from 'x' for derivative calculation.
       isdecr     O   Boolean indicating if the derivative is negative.
#### Detailed_Input
       udfunc     the routine that returns the value of the scalar quantity
                  function of interest at X. The calling sequence for UDFUNC is:

                     udfunc ( x, &value );

                  where:

                     x       the double precision value of the
                             independent variable of the function
                             at which to determine the scalar value.

                     value   the double precision value returned by
                             'udfunc' at 'x'.

                  Functionally:

                     value = udfunc ( x )

       x          a scalar double precision value at which to determine
                  the derivative of 'udfunc'.

                  For many SPICE uses, 'x' will represent ephemeris time,
                  expressed as seconds past J2000 TDB.

      dx         a scalar double precision value representing half the
                  interval in units of 'x' separating the evaluation
                  values of 'udfunc'; the evaluations occur at (x + dx)
                  and (x - dx).

                  'dx' may be negative but must be non-zero.
#### Detailed_Output
       isdecr   a scalar boolean indicating if the first derivative
                of 'udfunc' with respect to time at 'et' is less than
                zero.

                Functionally:

                  d udfunc(x) |
                  --          |  <  0
                  dx          |
                               x
#### Parameters
       None.
#### Exceptions
       1) A routine in the call tree of this routine signals
          SPICE(DIVIDEBYZERO) if DX has a value of zero.
#### Files
       If the evaluation of 'udfunc' requires SPICE kernel data, the
       appropriate kernels must be loaded before calling this routine.

          - SPK data: the calling application must load ephemeris data
            for the targets, observer, and any intermediate objects in
            a chain connecting the targets and observer for the time
            used in the evaluation. 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.

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

       Such kernel data are normally loaded once per program run, NOT
       every time this routine is called.
#### Particulars
       None.
#### Examples
       See gfuds_c.
#### Restrictions
       None.
#### Literature_References
       None.
#### Author_and_Institution
       N.J. Bachman   (JPL)
       E.D. Wright    (JPL)
#### Version
       -CSPICE Version 1.0.0, 31-MAR-2010 (EDW)
#### Index_Entries
       first derivative less-than zero
#### Link to routine uddc_c source file uddc_c.c

    Wed Jun  9 13:05:31 2010