void spkw12_c ( SpiceInt handle,
ConstSpiceChar * frame,
ConstSpiceChar * segid,
SpiceDouble step )
Write a type 12 segment to an SPK file.
Variable I/O Description
-------- --- --------------------------------------------------
MAXDEG P Maximum degree of interpolating polynomials.
TOLSCL P Scale factor used to compute time bound tolerance.
handle I Handle of an SPK file open for writing.
body I NAIF code for an ephemeris object.
center I NAIF code for center of motion of body.
frame I Reference frame name.
first I Start time of interval covered by segment.
last I End time of interval covered by segment.
segid I Segment identifier.
degree I Degree of interpolating polynomials.
n I Number of states.
states I Array of states.
epoch1 I Epoch of first state in states array.
step I Time step separating epochs of states.
MAXDEG P Maximum allowed degree of interpolating polynomial.
handle is the file handle of an SPK file that has been
opened for writing.
body is the NAIF integer code for an ephemeris object
whose state relative to another body is described
by the segment to be created.
center is the NAIF integer code for the center of motion
of the object identified by body.
frame is the NAIF name for a reference frame
relative to which the state information for body
last are, respectively, the start and stop times of
the time interval over which the segment defines
the state of body.
segid is the segment identifier. An SPK segment
identifier may contain up to 40 characters.
degree is the degree of the Hermite polynomials used to
interpolate the states. All components of the
state vectors are interpolated by polynomials of
n is the number of states in the input state vector
states contains a time-ordered array of geometric states
( x, y, z, dx/dt, dy/dt, dz/dt, in kilometers and
kilometers per second ) of body relative to center,
specified relative to frame.
epoch1 is the epoch corresponding to the first state in
the state array. Because extra states are needed
at the beginning and end of the segment in order
for the interpolation method to work, epoch1 will
normally precede first.
step is the time step separating the epochs of adjacent
states in the input state array. step is specified
None. See $Particulars for a description of the effect of this
The parameters below are declared in the Fortran include file
spk12.inc, which is part of the Fortran SPICE Toolkit (aka
SPICELIB). The values of those parameters are used in CSPICE code
generated by running f2c on SPICELIB source code. They are not
directly referenced by code in this module.
MAXDEG is the maximum allowed degree of the interpolating
The value of MAXDEG is 27.
TOLSCL is a tolerance scale factor (also called a
"relative tolerance") used for time coverage bound
checking. TOLSCL is unitless. TOLSCL produces a
tolerance value via the formula
TOL = TOLSCL * max( abs(first), abs(last) )
where `first' and `last' are the coverage time
bounds of a type 12 segment, expressed as seconds
past J2000 TDB.
The resulting parameter TOL is used as a tolerance
for comparing the input segment descriptor time
bounds to the first and last epoch covered by the
sequence of time intervals defined by the inputs
The value of TOLSCL is 1.e-13.
If any of the following exceptions occur, this routine will return
without creating a new segment.
1) If frame is not a recognized name, the error
SPICE(INVALIDREFFRAME) is signaled.
2) If the last non-blank character of segid occurs past index 40,
the error SPICE(SEGIDTOOLONG) is signaled.
3) If segid contains any nonprintable characters, the error
SPICE(NONPRINTABLECHARS) is signaled.
4) If degree is not at least 1 or is greater than MAXDEG, the
error SPICE(INVALIDDEGREE) is signaled.
5) If degree is not odd, the error SPICE(INVALIDDEGREE) is
6) If the number of states n is not at least (degree+1)/2,
the error SPICE(TOOFEWSTATES) will be signaled.
7) If first is greater than or equal to last then the error
SPICE(BADDESCRTIMES) will be signaled.
8) If step is non-positive, the error SPICE(INVALIDSTEPSIZE) will
9) If the start time of the first record exceeds the descriptor
begin time by more than a computed tolerance, or if the end time
of the last record precedes the descriptor end time by more than
a computed tolerance, the error SPICE(COVERAGEGAP) is signaled.
See the Parameters section above for a description of the
10) If either the input frame or segment ID string pointer is null,
the error SPICE(NULLPOINTER) is signaled.
11) If either the input frame or segment ID string is empty,
the error SPICE(EMPTYSTRING) is signaled.
A new type 12 SPK segment is written to the SPK file attached
This routine writes an SPK type 12 data segment to the open SPK
file according to the format described in the type 12 section of
the SPK Required Reading. The SPK file must have been opened with
Suppose that you have states and are prepared to produce
a segment of type 12 in an SPK file.
The following code fragment could be used to add the new segment
to a previously opened SPK file attached to handle. The file must
have been opened with write access.
Create a segment identifier.
#define SEGID "MY_SAMPLE_SPK_TYPE_12_SEGMENT"
Write the segment.
spkw12_c ( handle, body, center, frame,
first, last, segid, degree,
n, states, epoch1, step );
N.J. Bachman (JPL)
-CSPICE Version 2.0.0, 11-JAN-2014 (NJB)
Relaxed test on relationship between the time bounds of the
input record set (determined by `epoch1', `step', and `n') and
the descriptor bounds `first' and `last'. Now the descriptor
bounds may extend beyond the time bounds of the record set by a
ratio computed using the parameter TOLSCL (see Parameters above
for details). Added checks on input polynomial degree.
Renamed argument `epoch0' to `epoch1' for consistency with other
CSPICE and SPICELIB interfaces.
-CSPICE Version 1.0.0, 23-FEB-2000 (NJB)
write spk type_12 ephemeris data segment