/* pcke20.f -- translated by f2c (version 19980913).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/

#include "f2c.h"

/* $Procedure      PCKE20 ( PCK, evaluate record, type 20 ) */
/* Subroutine */ int pcke20_(doublereal *et, doublereal *record, doublereal *
	eulang)
{
    /* System generated locals */
    doublereal d__1;

    /* Builtin functions */
    double d_mod(doublereal *, doublereal *);

    /* Local variables */
    extern /* Subroutine */ int chkin_(char *, ftnlen), spke20_(doublereal *, 
	    doublereal *, doublereal *);
    extern doublereal twopi_(void);
    extern /* Subroutine */ int chkout_(char *, ftnlen);
    extern logical return_(void);

/* $ Abstract */

/*     Evaluate a single PCK data record from a segment of type 20 */
/*     (Chebyshev Polynomials, rotation derivative only). */

/* $ Disclaimer */

/*     THIS SOFTWARE AND ANY RELATED MATERIALS WERE CREATED BY THE */
/*     CALIFORNIA INSTITUTE OF TECHNOLOGY (CALTECH) UNDER A U.S. */
/*     GOVERNMENT CONTRACT WITH THE NATIONAL AERONAUTICS AND SPACE */
/*     ADMINISTRATION (NASA). THE SOFTWARE IS TECHNOLOGY AND SOFTWARE */
/*     PUBLICLY AVAILABLE UNDER U.S. EXPORT LAWS AND IS PROVIDED "AS-IS" */
/*     TO THE RECIPIENT WITHOUT WARRANTY OF ANY KIND, INCLUDING ANY */
/*     WARRANTIES OF PERFORMANCE OR MERCHANTABILITY OR FITNESS FOR A */
/*     PARTICULAR USE OR PURPOSE (AS SET FORTH IN UNITED STATES UCC */
/*     SECTIONS 2312-2313) OR FOR ANY PURPOSE WHATSOEVER, FOR THE */
/*     SOFTWARE AND RELATED MATERIALS, HOWEVER USED. */

/*     IN NO EVENT SHALL CALTECH, ITS JET PROPULSION LABORATORY, OR NASA */
/*     BE LIABLE FOR ANY DAMAGES AND/OR COSTS, INCLUDING, BUT NOT */
/*     LIMITED TO, INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND, */
/*     INCLUDING ECONOMIC DAMAGE OR INJURY TO PROPERTY AND LOST PROFITS, */
/*     REGARDLESS OF WHETHER CALTECH, JPL, OR NASA BE ADVISED, HAVE */
/*     REASON TO KNOW, OR, IN FACT, SHALL KNOW OF THE POSSIBILITY. */

/*     RECIPIENT BEARS ALL RISK RELATING TO QUALITY AND PERFORMANCE OF */
/*     THE SOFTWARE AND ANY RELATED MATERIALS, AND AGREES TO INDEMNIFY */
/*     CALTECH AND NASA FOR ALL THIRD-PARTY CLAIMS RESULTING FROM THE */
/*     ACTIONS OF RECIPIENT IN THE USE OF THE SOFTWARE. */

/* $ Required_Reading */

/*     PCK */

/* $ Keywords */

/*     ORIENTATION */
/*     ROTATION */
/*     TRANSFORMATION */

/* $ Declarations */
/* $ Brief_I/O */

/*     Variable  I/O  Description */
/*     --------  ---  -------------------------------------------------- */
/*     ET         I   Evaluation epoch. */
/*     RECORD     I   Data record. */
/*     EULANG     O   Euler angles and their derivatives. */

/* $ Detailed_Input */

/*     ET          is an epoch at which the Euler angles state is to be */
/*                 computed. The epoch is represented as seconds past */
/*                 J2000 TDB. */


/*     RECORD      is a data record which, when evaluated at epoch ET, */
/*                 will yield Euler angles and Euler angle rates */
/*                 representing the orientation and angular velocity, */
/*                 with respect to its base frame, of the reference */
/*                 frame associated with the input record. */

/*                 The structure of the record is as follows: */

/*                    +--------------------------------------+ */
/*                    | record size (excluding this element) | */
/*                    +--------------------------------------+ */
/*                    | Coverage interval midpoint           | */
/*                    +--------------------------------------+ */
/*                    | Coverage interval radius             | */
/*                    +--------------------------------------+ */
/*                    | Coeffs for ANGLE_1 rate              | */
/*                    +--------------------------------------+ */
/*                    | Coeffs for ANGLE_2 rate              | */
/*                    +--------------------------------------+ */
/*                    | Coeffs for ANGLE_3 rate              | */
/*                    +--------------------------------------+ */
/*                    | ANGLE_1 at interval midpoint         | */
/*                    +--------------------------------------+ */
/*                    | ANGLE_2 at interval midpoint         | */
/*                    +--------------------------------------+ */
/*                    | ANGLE_3 at interval midpoint         | */
/*                    +--------------------------------------+ */

/*                 In the above record */

/*                    - Times are expressed as seconds past J2000 TDB. */
/*                    - Angular components have units of radians. */
/*                    - Rate coefficients have units of radians/s. */

/*                 RECORD must be declared by the caller with size large */
/*                 enough to accommodate the largest record that can be */
/*                 returned by PCKR20. */


/* $ Detailed_Output */

/*     EULANG      is a 6-vector containing Euler angles and their */
/*                 derivatives at time ET. The angles occupy the first */
/*                 three elements of EULANG; the rates follow. The order */
/*                 of the components is */

/*                    ( ANGLE_1, ANGLE_2, ANGLE_3, */
/*                      rate_1,  rate_2,  rate_3  ) */

/*                 The angular units are radians; the rate units are */
/*                 radians/second. */

/*                 The Euler angles represent the orientation, relative */
/*                 to its base frame, of the PCK frame associated with */
/*                 the input record. The angles, which are numbered */
/*                 according to their ordinal position in the logical */
/*                 records, define a transformation matrix R as follows: */

/*                    R = [ ANGLE_3 ]  [ ANGLE_2 ]  [ ANGLE_1 ] */
/*                                   3            1            3 */

/*                 Here the notation */

/*                    [ THETA ] */
/*                             i */

/*                 denotes a reference frame rotation of THETA radians */
/*                 in the right-hand sense about the ith coordinate */
/*                 axis. See the Rotation Required Reading for further */
/*                 discussion of this notation. */

/*                 The matrix R transforms vectors expressed in the base */
/*                 frame to vectors expressed in the PCK frame associated */
/*                 with RECORD by left multiplication: */

/*                    V    = R * V */
/*                     PCK        FRAME */

/*                 In cases where the PCK frame is a body-fixed, */
/*                 right-handed frame with its +Z axis aligned with a */
/*                 body's north pole, the orientation angles are related */
/*                 to right ascension (RA) and declination (DEC) of the */
/*                 PCK frame's north pole, and prime meridian */
/*                 orientation (W), by the equations */

/*                    ANGLE_1 = RA   + pi/2 radians */
/*                    ANGLE_2 = pi/2 - DEC  radians */
/*                    ANGLE_3 = W           radians */

/* $ Parameters */

/*     None. */

/* $ Exceptions */

/*     1) If the input record contains an invalid coefficient count, */
/*        the error will be diagnosed by a routine in the call tree of */
/*        this routine. */

/*     2) If the input record contains invalid domain transformation */
/*        parameters, the error will be diagnosed by a routine in the */
/*        call tree of this routine. */

/* $ Files */

/*     None. */

/* $ Particulars */

/*     The exact format and structure of type 20 (Chebyshev polynomials, */
/*     position only) segments are described in the PCK Required Reading */
/*     file. */

/*     A type 20 segment contains three sets of Chebyshev coefficients, */
/*     one set each for the derivatives with respect to time of the */
/*     Euler angles phi, delta and psi. PCKE20 calls the routine SPKE20 */
/*     for each set to evaluate the polynomial and its first derivative. */

/* $ Examples */

/*     The PCKEnn routines are almost always used in conjunction with */
/*     the corresponding PCKRnn routines, which read the records from */
/*     binary PCK files. */

/*     The data returned by the PCKRnn routine are in their rawest form, */
/*     taken directly from the segment.  As such, they will be */
/*     meaningless to a user unless he/she understands the structure of */
/*     the data type completely. Given that understanding, however, the */
/*     PCKRnn routines might be used to examine raw segment data before */
/*     evaluating it with the PCKEnn routines. */


/*     Here we load a binary PCK files and use PCKE20 to get the */
/*     Euler angles. */

/*  C */
/*  C     Load binary PCK file. */
/*  C */
/*        CALL PCKLOF ('example.pck', HANDLE) */

/*  C */
/*  C     Get a segment applicable to a specified body and epoch. */
/*  C */
/*        CALL PCKSFS ( BODY, ET, HANDLE, DESCR, IDENT, FOUND ) */

/*        IF ( FOUND ) THEN */
/*  C */
/*  C        Look at parts of the descriptor. */
/*  C */
/*           CALL DAFUS ( DESCR, ND, NI, DCD, ICD ) */
/*           TYPE   = ICD( NT ) */
/*           REF    = ICD( NR ) */

/*           IF ( TYPE .EQ. 20 ) THEN */
/*  C */
/*  C           Read in Chebyshev coefficients from segment. */
/*  C */
/*              CALL PCKR20 ( HANDLE, DESCR, ET, RECORD ) */
/*  C */
/*  C           Call evaluation routine to get Euler angles */
/*  C           phi, delta, w. */
/*  C */
/*              CALL PCKE20 ( ET, RECORD, EULANG ) */


/*     The Euler angles and their derivatives are returned */
/*     in EULANG. */

/* $ Restrictions */

/*     None. */

/* $ Literature_References */

/*     None. */

/* $ Author_and_Institution */

/*     N.J. Bachman (JPL) */
/*     K.S. Zukor   (JPL) */

/* $ Version */

/* -    SPICELIB Version 1.0.0, 17-JAN-2014 (NJB) (KSZ) */

/* -& */
/* $ Index_Entries */

/*     evaluate pck_type_20 record */

/* -& */

/*     SPICELIB functions */


/*     Standard SPICE error handling. */

    if (return_()) {
	return 0;
    }
    chkin_("PCKE20", (ftnlen)6);

/*     Call evaluation routine to get Euler angles */
/*     phi, delta, w. */

    spke20_(et, record, eulang);

/*     Map the third angle into the range (-2pi, 2pi). */

    d__1 = twopi_();
    eulang[2] = d_mod(&eulang[2], &d__1);
    chkout_("PCKE20", (ftnlen)6);
    return 0;
} /* pcke20_ */

