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//
// GENERATED FILE
//
use super::*;
use crate::SpiceContext;
use f2rust_std::*;
/// Evaluate SPK record, type 5
///
/// Evaluate a single SPK data record from a segment of type 5
/// (two body propagation between discrete state vectors).
///
/// # Required Reading
///
/// * [SPK](crate::required_reading::spk)
///
/// # Brief I/O
///
/// ```text
/// VARIABLE I/O DESCRIPTION
/// -------- --- --------------------------------------------------
/// ET I Target epoch.
/// RECORD I Data record.
/// STATE O State (position and velocity).
/// ```
///
/// # Detailed Input
///
/// ```text
/// ET is a target epoch, specified as ephemeris seconds past
/// J2000, at which a state vector is to be computed.
///
/// RECORD is a data record which, when evaluated at epoch ET,
/// will give the state (position and velocity) of some
/// body, relative to some center, in some inertial
/// reference frame.
///
/// The structure of RECORD is:
///
/// RECORD(1)
/// . state of the body at epoch 1.
/// .
/// .
/// RECORD(6)
///
/// RECORD(7)
/// .
/// . state of the body at epoch 2.
/// .
/// RECORD(12)
/// RECORD(13) epoch 1 in seconds past 2000.
/// RECORD(14) epoch 2 in seconds past 2000.
/// RECORD(15) GM for the center of motion.
///
/// Epoch 1 and epoch 2 are the times in the segment that
/// bracket ET. If ET is less than the first time in the
/// segment then both epochs 1 and 2 are equal to the
/// first time. And if ET is greater than the last time
/// then, epochs 1 and 2 are set equal to this last time.
/// ```
///
/// # Detailed Output
///
/// ```text
/// STATE is the state produced by evaluating RECORD at ET.
/// Units are km and km/sec.
/// ```
///
/// # Exceptions
///
/// ```text
/// 1) If there is a problem propagating, subject to the laws of two
/// body motion, either of the states from RECORD to the requested
/// time ET, an error is signaled by a routine in the call tree of
/// this routine.
/// ```
///
/// # Particulars
///
/// ```text
/// This routine interpolates a state from the two reference states
/// contained in RECORD.
///
/// It is assumed that this routine is used in conjunction with
/// the routine SPKR05 as shown here:
///
/// CALL SPKR05 ( HANDLE, DESCR, ET, RECORD )
/// CALL SPKE05 ( ET, RECORD, STATE )
///
/// Where it is known in advance that the HANDLE, DESCR pair points
/// to a type 05 data segment.
/// ```
///
/// # Examples
///
/// ```text
/// The SPKEnn routines are almost always used in conjunction with
/// the corresponding SPKRnn routines, which read the records from
/// SPK files.
///
/// The data returned by the SPKRnn routine is in its rawest form,
/// taken directly from the segment. As such, it will be meaningless
/// to a user unless he/she understands the structure of the data type
/// completely. Given that understanding, however, the SPKRnn
/// routines might be used to examine raw segment data before
/// evaluating it with the SPKEnn routines.
///
///
/// C
/// C Get a segment applicable to a specified body and epoch.
/// C
/// CALL SPKSFS ( BODY, ET, HANDLE, DESCR, IDENT, FOUND )
///
/// C
/// C Look at parts of the descriptor.
/// C
/// CALL DAFUS ( DESCR, 2, 6, DCD, ICD )
/// CENTER = ICD( 2 )
/// REF = ICD( 3 )
/// TYPE = ICD( 4 )
///
/// IF ( TYPE .EQ. 5 ) THEN
///
/// CALL SPKR05 ( HANDLE, DESCR, ET, RECORD )
/// .
/// . Look at the RECORD data.
/// .
/// CALL SPKE05 ( ET, RECORD, STATE )
/// .
/// . Check out the evaluated state.
/// .
/// END IF
/// ```
///
/// # Author and Institution
///
/// ```text
/// N.J. Bachman (JPL)
/// J. Diaz del Rio (ODC Space)
/// K.R. Gehringer (JPL)
/// J.M. Lynch (JPL)
/// W.L. Taber (JPL)
/// I.M. Underwood (JPL)
/// ```
///
/// # Version
///
/// ```text
/// - SPICELIB Version 1.3.0, 12-AUG-2021 (JDR)
///
/// Added IMPLICIT NONE statement.
///
/// Edited the header to comply with NAIF standard.
///
/// - SPICELIB Version 1.2.0, 31-AUG-2005 (NJB)
///
/// Updated to remove non-standard use of duplicate arguments
/// in VADD call.
///
/// - SPICELIB Version 1.1.0, 29-FEB-1996 (KRG)
///
/// The declaration for the SPICELIB function PI is now
/// preceded by an EXTERNAL statement declaring PI to be an
/// external function. This removes a conflict with any
/// compilers that have a PI intrinsic function.
///
/// - SPICELIB Version 1.0.0, 01-APR-1992 (JML) (WLT) (IMU)
/// ```
///
/// # Revisions
///
/// ```text
/// - SPICELIB Version 1.2.0, 31-AUG-2005 (NJB)
///
/// Updated to remove non-standard use of duplicate arguments
/// in VADD call.
///
/// - SPICELIB Version 1.1.0, 29-FEB-1996 (KRG)
///
/// The declaration for the SPICELIB function PI is now
/// preceded by an EXTERNAL statement declaring PI to be an
/// external function. This removes a conflict with any
/// compilers that have a PI intrinsic function.
///
/// - SPICELIB Version 1.0.0, 01-APR-1992 (JML) (WLT) (IMU)
/// ```
pub fn spke05(
ctx: &mut SpiceContext,
et: f64,
record: &[f64],
state: &mut [f64; 6],
) -> crate::Result<()> {
SPKE05(et, record, state, ctx.raw_context())?;
ctx.handle_errors()?;
Ok(())
}
//$Procedure SPKE05 ( Evaluate SPK record, type 5 )
pub fn SPKE05(
ET: f64,
RECORD: &[f64],
STATE: &mut [f64],
ctx: &mut Context,
) -> f2rust_std::Result<()> {
let RECORD = DummyArray::new(RECORD, 1..);
let mut STATE = DummyArrayMut::new(STATE, 1..=6);
let mut ARG: f64 = 0.0;
let mut DARGDT: f64 = 0.0;
let mut DENOM: f64 = 0.0;
let mut DWDT: f64 = 0.0;
let mut GM: f64 = 0.0;
let mut NUMER: f64 = 0.0;
let mut PV = StackArray2D::<f64, 12>::new(1..=6, 1..=2);
let mut S1 = StackArray::<f64, 6>::new(1..=6);
let mut S2 = StackArray::<f64, 6>::new(1..=6);
let mut T1: f64 = 0.0;
let mut T2: f64 = 0.0;
let mut VCOMP = StackArray::<f64, 3>::new(1..=3);
let mut VEL = StackArray::<f64, 3>::new(1..=3);
let mut W: f64 = 0.0;
//
// SPICELIB functions
//
//
// Local variables
//
//
// Standard SPICE error handling.
//
if RETURN(ctx) {
return Ok(());
} else {
CHKIN(b"SPKE05", ctx)?;
}
//
// Unpack the record, for easier reading.
//
MOVED(RECORD.as_slice(), 12, PV.as_slice_mut());
T1 = RECORD[13];
T2 = RECORD[14];
GM = RECORD[15];
//
// Evaluate the two states. Call them s_1(t) and s_2(t).
// Let the position and velocity components be: p_1, v_1, p_2, v_2.
//
// The final position is a weighted average.
//
// Let
//
// W(t) = 0.5 + 0.5*COS( PI*(t-t1)/(t2-t1) )
//
// then
//
// p = W(t)*p_1(t) + (1 - W(t))*p_2(t)
// v = W(t)*v_1(t) + (1 - W(t))*v_2(t) + W'(t)*(p_1(t) - p_2(t))
//
// If t1 = t2, the state is just s(t1).
//
//
// Note: there are a number of weighting schemes we could have
// used. This one has the nice property that
//
// The graph of W is symmetric about the point
//
//
// ( (t1+t2)/2, W( (t1+t2)/2 )
//
// The range of W is from 1 to 0. And the derivative of W is
// symmetric and zero at both t1 and t2.
//
//
if (T1 != T2) {
PROP2B(GM, PV.subarray([1, 1]), (ET - T1), S1.as_slice_mut(), ctx)?;
PROP2B(GM, PV.subarray([1, 2]), (ET - T2), S2.as_slice_mut(), ctx)?;
NUMER = (ET - T1);
DENOM = (T2 - T1);
ARG = ((NUMER * PI(ctx)) / DENOM);
DARGDT = (PI(ctx) / DENOM);
W = (0.5 + (0.5 * f64::cos(ARG)));
DWDT = -((0.5 * f64::sin(ARG)) * DARGDT);
VLCOMG(
6,
W,
S1.as_slice(),
(1.0 - W),
S2.as_slice(),
STATE.as_slice_mut(),
);
VLCOM(
DWDT,
S1.as_slice(),
-DWDT,
S2.as_slice(),
VCOMP.as_slice_mut(),
);
VADD(STATE.subarray(4), VCOMP.as_slice(), VEL.as_slice_mut());
VEQU(VEL.as_slice(), STATE.subarray_mut(4));
} else {
PROP2B(
GM,
PV.subarray([1, 1]),
(ET - T1),
STATE.as_slice_mut(),
ctx,
)?;
}
CHKOUT(b"SPKE05", ctx)?;
Ok(())
}