#include "sofa.h"

void iauNut80(double date1, double date2, double *dpsi, double *deps)
/*
**  - - - - - - - - -
**   i a u N u t 8 0
**  - - - - - - - - -
**
**  Nutation, IAU 1980 model.
**
**  This function is part of the International Astronomical Union's
**  SOFA (Standards Of Fundamental Astronomy) software collection.
**
**  Status:  canonical model.
**
**  Given:
**     date1,date2   double    TT as a 2-part Julian Date (Note 1)
**
**  Returned:
**     dpsi          double    nutation in longitude (radians)
**     deps          double    nutation in obliquity (radians)
**
**  Notes:
**
**  1) The TT date date1+date2 is a Julian Date, apportioned in any
**     convenient way between the two arguments.  For example,
**     JD(TT)=2450123.7 could be expressed in any of these ways,
**     among others:
**
**            date1          date2
**
**         2450123.7           0.0       (JD method)
**         2451545.0       -1421.3       (J2000 method)
**         2400000.5       50123.2       (MJD method)
**         2450123.5           0.2       (date & time method)
**
**     The JD method is the most natural and convenient to use in
**     cases where the loss of several decimal digits of resolution
**     is acceptable.  The J2000 method is best matched to the way
**     the argument is handled internally and will deliver the
**     optimum resolution.  The MJD method and the date & time methods
**     are both good compromises between resolution and convenience.
**
**  2) The nutation components are with respect to the ecliptic of
**     date.
**
**  Called:
**     iauAnpm      normalize angle into range +/- pi
**
**  Reference:
**
**     Explanatory Supplement to the Astronomical Almanac,
**     P. Kenneth Seidelmann (ed), University Science Books (1992),
**     Section 3.222 (p111).
**
**  This revision:  2019 June 23
**
**  SOFA release 2019-07-22
**
**  Copyright (C) 2019 IAU SOFA Board.  See notes at end.
*/
{
   double t, el, elp, f, d, om, dp, de, arg, s, c;
   int j;

/* Units of 0.1 milliarcsecond to radians */
   const double U2R = DAS2R / 1e4;

/* ------------------------------------------------ */
/* Table of multiples of arguments and coefficients */
/* ------------------------------------------------ */

/* The units for the sine and cosine coefficients are 0.1 mas and */
/* the same per Julian century */

   static const struct {
      int nl,nlp,nf,nd,nom; /* coefficients of l,l',F,D,Om */
      double sp,spt;        /* longitude sine, 1 and t coefficients */
      double ce,cet;        /* obliquity cosine, 1 and t coefficients */
   } x[] = {

   /* 1-10 */
      {  0,  0,  0,  0,  1, -171996.0, -174.2,  92025.0,    8.9 },
      {  0,  0,  0,  0,  2,    2062.0,    0.2,   -895.0,    0.5 },
      { -2,  0,  2,  0,  1,      46.0,    0.0,    -24.0,    0.0 },
      {  2,  0, -2,  0,  0,      11.0,    0.0,      0.0,    0.0 },
      { -2,  0,  2,  0,  2,      -3.0,    0.0,      1.0,    0.0 },
      {  1, -1,  0, -1,  0,      -3.0,    0.0,      0.0,    0.0 },
      {  0, -2,  2, -2,  1,      -2.0,    0.0,      1.0,    0.0 },
      {  2,  0, -2,  0,  1,       1.0,    0.0,      0.0,    0.0 },
      {  0,  0,  2, -2,  2,  -13187.0,   -1.6,   5736.0,   -3.1 },
      {  0,  1,  0,  0,  0,    1426.0,   -3.4,     54.0,   -0.1 },

   /* 11-20 */
      {  0,  1,  2, -2,  2,    -517.0,    1.2,    224.0,   -0.6 },
      {  0, -1,  2, -2,  2,     217.0,   -0.5,    -95.0,    0.3 },
      {  0,  0,  2, -2,  1,     129.0,    0.1,    -70.0,    0.0 },
      {  2,  0,  0, -2,  0,      48.0,    0.0,      1.0,    0.0 },
      {  0,  0,  2, -2,  0,     -22.0,    0.0,      0.0,    0.0 },
      {  0,  2,  0,  0,  0,      17.0,   -0.1,      0.0,    0.0 },
      {  0,  1,  0,  0,  1,     -15.0,    0.0,      9.0,    0.0 },
      {  0,  2,  2, -2,  2,     -16.0,    0.1,      7.0,    0.0 },
      {  0, -1,  0,  0,  1,     -12.0,    0.0,      6.0,    0.0 },
      { -2,  0,  0,  2,  1,      -6.0,    0.0,      3.0,    0.0 },

   /* 21-30 */
      {  0, -1,  2, -2,  1,      -5.0,    0.0,      3.0,    0.0 },
      {  2,  0,  0, -2,  1,       4.0,    0.0,     -2.0,    0.0 },
      {  0,  1,  2, -2,  1,       4.0,    0.0,     -2.0,    0.0 },
      {  1,  0,  0, -1,  0,      -4.0,    0.0,      0.0,    0.0 },
      {  2,  1,  0, -2,  0,       1.0,    0.0,      0.0,    0.0 },
      {  0,  0, -2,  2,  1,       1.0,    0.0,      0.0,    0.0 },
      {  0,  1, -2,  2,  0,      -1.0,    0.0,      0.0,    0.0 },
      {  0,  1,  0,  0,  2,       1.0,    0.0,      0.0,    0.0 },
      { -1,  0,  0,  1,  1,       1.0,    0.0,      0.0,    0.0 },
      {  0,  1,  2, -2,  0,      -1.0,    0.0,      0.0,    0.0 },

   /* 31-40 */
      {  0,  0,  2,  0,  2,   -2274.0,   -0.2,    977.0,   -0.5 },
      {  1,  0,  0,  0,  0,     712.0,    0.1,     -7.0,    0.0 },
      {  0,  0,  2,  0,  1,    -386.0,   -0.4,    200.0,    0.0 },
      {  1,  0,  2,  0,  2,    -301.0,    0.0,    129.0,   -0.1 },
      {  1,  0,  0, -2,  0,    -158.0,    0.0,     -1.0,    0.0 },
      { -1,  0,  2,  0,  2,     123.0,    0.0,    -53.0,    0.0 },
      {  0,  0,  0,  2,  0,      63.0,    0.0,     -2.0,    0.0 },
      {  1,  0,  0,  0,  1,      63.0,    0.1,    -33.0,    0.0 },
      { -1,  0,  0,  0,  1,     -58.0,   -0.1,     32.0,    0.0 },
      { -1,  0,  2,  2,  2,     -59.0,    0.0,     26.0,    0.0 },

   /* 41-50 */
      {  1,  0,  2,  0,  1,     -51.0,    0.0,     27.0,    0.0 },
      {  0,  0,  2,  2,  2,     -38.0,    0.0,     16.0,    0.0 },
      {  2,  0,  0,  0,  0,      29.0,    0.0,     -1.0,    0.0 },
      {  1,  0,  2, -2,  2,      29.0,    0.0,    -12.0,    0.0 },
      {  2,  0,  2,  0,  2,     -31.0,    0.0,     13.0,    0.0 },
      {  0,  0,  2,  0,  0,      26.0,    0.0,     -1.0,    0.0 },
      { -1,  0,  2,  0,  1,      21.0,    0.0,    -10.0,    0.0 },
      { -1,  0,  0,  2,  1,      16.0,    0.0,     -8.0,    0.0 },
      {  1,  0,  0, -2,  1,     -13.0,    0.0,      7.0,    0.0 },
      { -1,  0,  2,  2,  1,     -10.0,    0.0,      5.0,    0.0 },

   /* 51-60 */
      {  1,  1,  0, -2,  0,      -7.0,    0.0,      0.0,    0.0 },
      {  0,  1,  2,  0,  2,       7.0,    0.0,     -3.0,    0.0 },
      {  0, -1,  2,  0,  2,      -7.0,    0.0,      3.0,    0.0 },
      {  1,  0,  2,  2,  2,      -8.0,    0.0,      3.0,    0.0 },
      {  1,  0,  0,  2,  0,       6.0,    0.0,      0.0,    0.0 },
      {  2,  0,  2, -2,  2,       6.0,    0.0,     -3.0,    0.0 },
      {  0,  0,  0,  2,  1,      -6.0,    0.0,      3.0,    0.0 },
      {  0,  0,  2,  2,  1,      -7.0,    0.0,      3.0,    0.0 },
      {  1,  0,  2, -2,  1,       6.0,    0.0,     -3.0,    0.0 },
      {  0,  0,  0, -2,  1,      -5.0,    0.0,      3.0,    0.0 },

   /* 61-70 */
      {  1, -1,  0,  0,  0,       5.0,    0.0,      0.0,    0.0 },
      {  2,  0,  2,  0,  1,      -5.0,    0.0,      3.0,    0.0 },
      {  0,  1,  0, -2,  0,      -4.0,    0.0,      0.0,    0.0 },
      {  1,  0, -2,  0,  0,       4.0,    0.0,      0.0,    0.0 },
      {  0,  0,  0,  1,  0,      -4.0,    0.0,      0.0,    0.0 },
      {  1,  1,  0,  0,  0,      -3.0,    0.0,      0.0,    0.0 },
      {  1,  0,  2,  0,  0,       3.0,    0.0,      0.0,    0.0 },
      {  1, -1,  2,  0,  2,      -3.0,    0.0,      1.0,    0.0 },
      { -1, -1,  2,  2,  2,      -3.0,    0.0,      1.0,    0.0 },
      { -2,  0,  0,  0,  1,      -2.0,    0.0,      1.0,    0.0 },

   /* 71-80 */
      {  3,  0,  2,  0,  2,      -3.0,    0.0,      1.0,    0.0 },
      {  0, -1,  2,  2,  2,      -3.0,    0.0,      1.0,    0.0 },
      {  1,  1,  2,  0,  2,       2.0,    0.0,     -1.0,    0.0 },
      { -1,  0,  2, -2,  1,      -2.0,    0.0,      1.0,    0.0 },
      {  2,  0,  0,  0,  1,       2.0,    0.0,     -1.0,    0.0 },
      {  1,  0,  0,  0,  2,      -2.0,    0.0,      1.0,    0.0 },
      {  3,  0,  0,  0,  0,       2.0,    0.0,      0.0,    0.0 },
      {  0,  0,  2,  1,  2,       2.0,    0.0,     -1.0,    0.0 },
      { -1,  0,  0,  0,  2,       1.0,    0.0,     -1.0,    0.0 },
      {  1,  0,  0, -4,  0,      -1.0,    0.0,      0.0,    0.0 },

   /* 81-90 */
      { -2,  0,  2,  2,  2,       1.0,    0.0,     -1.0,    0.0 },
      { -1,  0,  2,  4,  2,      -2.0,    0.0,      1.0,    0.0 },
      {  2,  0,  0, -4,  0,      -1.0,    0.0,      0.0,    0.0 },
      {  1,  1,  2, -2,  2,       1.0,    0.0,     -1.0,    0.0 },
      {  1,  0,  2,  2,  1,      -1.0,    0.0,      1.0,    0.0 },
      { -2,  0,  2,  4,  2,      -1.0,    0.0,      1.0,    0.0 },
      { -1,  0,  4,  0,  2,       1.0,    0.0,      0.0,    0.0 },
      {  1, -1,  0, -2,  0,       1.0,    0.0,      0.0,    0.0 },
      {  2,  0,  2, -2,  1,       1.0,    0.0,     -1.0,    0.0 },
      {  2,  0,  2,  2,  2,      -1.0,    0.0,      0.0,    0.0 },

   /* 91-100 */
      {  1,  0,  0,  2,  1,      -1.0,    0.0,      0.0,    0.0 },
      {  0,  0,  4, -2,  2,       1.0,    0.0,      0.0,    0.0 },
      {  3,  0,  2, -2,  2,       1.0,    0.0,      0.0,    0.0 },
      {  1,  0,  2, -2,  0,      -1.0,    0.0,      0.0,    0.0 },
      {  0,  1,  2,  0,  1,       1.0,    0.0,      0.0,    0.0 },
      { -1, -1,  0,  2,  1,       1.0,    0.0,      0.0,    0.0 },
      {  0,  0, -2,  0,  1,      -1.0,    0.0,      0.0,    0.0 },
      {  0,  0,  2, -1,  2,      -1.0,    0.0,      0.0,    0.0 },
      {  0,  1,  0,  2,  0,      -1.0,    0.0,      0.0,    0.0 },
      {  1,  0, -2, -2,  0,      -1.0,    0.0,      0.0,    0.0 },

   /* 101-106 */
      {  0, -1,  2,  0,  1,      -1.0,    0.0,      0.0,    0.0 },
      {  1,  1,  0, -2,  1,      -1.0,    0.0,      0.0,    0.0 },
      {  1,  0, -2,  2,  0,      -1.0,    0.0,      0.0,    0.0 },
      {  2,  0,  0,  2,  0,       1.0,    0.0,      0.0,    0.0 },
      {  0,  0,  2,  4,  2,      -1.0,    0.0,      0.0,    0.0 },
      {  0,  1,  0,  1,  0,       1.0,    0.0,      0.0,    0.0 }
   };

/* Number of terms in the series */
   const int NT = (int) (sizeof x / sizeof x[0]);

/* ------------------------------------------------------------------ */

/* Interval between fundamental epoch J2000.0 and given date (JC). */
   t = ((date1 - DJ00) + date2) / DJC;

/* --------------------- */
/* Fundamental arguments */
/* --------------------- */

/* Mean longitude of Moon minus mean longitude of Moon's perigee. */
   el = iauAnpm(
        (485866.733 + (715922.633 + (31.310 + 0.064 * t) * t) * t)
        * DAS2R + fmod(1325.0 * t, 1.0) * D2PI);

/* Mean longitude of Sun minus mean longitude of Sun's perigee. */
   elp = iauAnpm(
         (1287099.804 + (1292581.224 + (-0.577 - 0.012 * t) * t) * t)
         * DAS2R + fmod(99.0 * t, 1.0) * D2PI);

/* Mean longitude of Moon minus mean longitude of Moon's node. */
   f = iauAnpm(
       (335778.877 + (295263.137 + (-13.257 + 0.011 * t) * t) * t)
       * DAS2R + fmod(1342.0 * t, 1.0) * D2PI);

/* Mean elongation of Moon from Sun. */
   d = iauAnpm(
       (1072261.307 + (1105601.328 + (-6.891 + 0.019 * t) * t) * t)
       * DAS2R + fmod(1236.0 * t, 1.0) * D2PI);

/* Longitude of the mean ascending node of the lunar orbit on the */
/* ecliptic, measured from the mean equinox of date. */
   om = iauAnpm(
        (450160.280 + (-482890.539 + (7.455 + 0.008 * t) * t) * t)
        * DAS2R + fmod(-5.0 * t, 1.0) * D2PI);

/* --------------- */
/* Nutation series */
/* --------------- */

/* Initialize nutation components. */
   dp = 0.0;
   de = 0.0;

/* Sum the nutation terms, ending with the biggest. */
   for (j = NT-1; j >= 0; j--) {

   /* Form argument for current term. */
      arg = (double)x[j].nl  * el
          + (double)x[j].nlp * elp
          + (double)x[j].nf  * f
          + (double)x[j].nd  * d
          + (double)x[j].nom * om;

   /* Accumulate current nutation term. */
      s = x[j].sp + x[j].spt * t;
      c = x[j].ce + x[j].cet * t;
      if (s != 0.0) dp += s * sin(arg);
      if (c != 0.0) de += c * cos(arg);
   }

/* Convert results from 0.1 mas units to radians. */
   *dpsi = dp * U2R;
   *deps = de * U2R;

   return;

/*----------------------------------------------------------------------
**
**  Copyright (C) 2019
**  Standards Of Fundamental Astronomy Board
**  of the International Astronomical Union.
**
**  =====================
**  SOFA Software License
**  =====================
**
**  NOTICE TO USER:
**
**  BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
**  CONDITIONS WHICH APPLY TO ITS USE.
**
**  1. The Software is owned by the IAU SOFA Board ("SOFA").
**
**  2. Permission is granted to anyone to use the SOFA software for any
**     purpose, including commercial applications, free of charge and
**     without payment of royalties, subject to the conditions and
**     restrictions listed below.
**
**  3. You (the user) may copy and distribute SOFA source code to others,
**     and use and adapt its code and algorithms in your own software,
**     on a world-wide, royalty-free basis.  That portion of your
**     distribution that does not consist of intact and unchanged copies
**     of SOFA source code files is a "derived work" that must comply
**     with the following requirements:
**
**     a) Your work shall be marked or carry a statement that it
**        (i) uses routines and computations derived by you from
**        software provided by SOFA under license to you; and
**        (ii) does not itself constitute software provided by and/or
**        endorsed by SOFA.
**
**     b) The source code of your derived work must contain descriptions
**        of how the derived work is based upon, contains and/or differs
**        from the original SOFA software.
**
**     c) The names of all routines in your derived work shall not
**        include the prefix "iau" or "sofa" or trivial modifications
**        thereof such as changes of case.
**
**     d) The origin of the SOFA components of your derived work must
**        not be misrepresented;  you must not claim that you wrote the
**        original software, nor file a patent application for SOFA
**        software or algorithms embedded in the SOFA software.
**
**     e) These requirements must be reproduced intact in any source
**        distribution and shall apply to anyone to whom you have
**        granted a further right to modify the source code of your
**        derived work.
**
**     Note that, as originally distributed, the SOFA software is
**     intended to be a definitive implementation of the IAU standards,
**     and consequently third-party modifications are discouraged.  All
**     variations, no matter how minor, must be explicitly marked as
**     such, as explained above.
**
**  4. You shall not cause the SOFA software to be brought into
**     disrepute, either by misuse, or use for inappropriate tasks, or
**     by inappropriate modification.
**
**  5. The SOFA software is provided "as is" and SOFA makes no warranty
**     as to its use or performance.   SOFA does not and cannot warrant
**     the performance or results which the user may obtain by using the
**     SOFA software.  SOFA makes no warranties, express or implied, as
**     to non-infringement of third party rights, merchantability, or
**     fitness for any particular purpose.  In no event will SOFA be
**     liable to the user for any consequential, incidental, or special
**     damages, including any lost profits or lost savings, even if a
**     SOFA representative has been advised of such damages, or for any
**     claim by any third party.
**
**  6. The provision of any version of the SOFA software under the terms
**     and conditions specified herein does not imply that future
**     versions will also be made available under the same terms and
**     conditions.
*
**  In any published work or commercial product which uses the SOFA
**  software directly, acknowledgement (see www.iausofa.org) is
**  appreciated.
**
**  Correspondence concerning SOFA software should be addressed as
**  follows:
**
**      By email:  sofa@ukho.gov.uk
**      By post:   IAU SOFA Center
**                 HM Nautical Almanac Office
**                 UK Hydrographic Office
**                 Admiralty Way, Taunton
**                 Somerset, TA1 2DN
**                 United Kingdom
**
**--------------------------------------------------------------------*/
}
