/************************************************************************

COMPUTATION OF THE COORDINATES OF THE URANIAN SATELLITES (GUST86),
version 0.1 (1988,1995) by LASKAR J. and JACOBSON, R. can be found at
ftp://ftp.imcce.fr/pub/ephem/satel/gust86

I (Johannes Gajdosik) have just taken the Fortran code and data
obtained from above and rearranged it into this piece of software.

I can neigther allow nor forbid the usage of the GUST86 theory.
The copyright notice below covers not the works of LASKAR J. and JACOBSON, R.,
but just my work, that is the compilation of the GUST86 theory
into the software supplied in this file.


Copyright (c) 2005 Johannes Gajdosik

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

My implementation of GUST86 has the following modifications:
1) Rotate results to "dynamical equinox and ecliptic J2000",
   the reference frame of VSOP87 and VSOP87A:
   The rotation matrix Gust86ToJ2000 can be derived from gust86.f,
   the rotation J2000ToVsop87 can be derived from vsop87.doc.
2) units used in calculations: julian day, AU, rad
3) use the same function EllipticToRectangular that I use in TASS17.
4) calculate the orbital elements not for every new jd but rather reuse
   the previousely calculated elements if possible

****************************************************************/

#include "gust86.h"
#include "calc_interpolated_elements.h"
#include "elliptic_to_rectangular.h"

#include <math.h>

#ifndef M_PI
#define M_PI           3.14159265358979323846
#endif

static
const double fqn[5] = {4.44519055,
                       2.492952519,
                       1.516148111,
                       0.721718509,
                       0.46669212};
static
const double fqe[5] = {20.082*M_PI/(180*365.25),
                        6.217*M_PI/(180*365.25),
                        2.865*M_PI/(180*365.25),
                        2.078*M_PI/(180*365.25),
                        0.386*M_PI/(180*365.25)};
static
const double fqi[5] = {-20.309*M_PI/(180*365.25),
                        -6.288*M_PI/(180*365.25),
                        -2.836*M_PI/(180*365.25),
                        -1.843*M_PI/(180*365.25),
                        -0.259*M_PI/(180*365.25)};
static
const double phn[5] = {-0.238051,
                        3.098046,
                        2.285402,
                        0.856359,
                       -0.915592};
static
const double phe[5] = {0.611392,
                       2.408974,
                       2.067774,
                       0.735131,
                       0.426767};
static
const double phi[5] = {5.702313,
                       0.395757,
                       0.589326,
                       1.746237,
                       4.206896};

void CalcGust86Elem(double t,double elem[5*6]) {
  double an[5],ae[5],ai[5];
  int i;
  for (i=0;i<5;i++) {
    an[i] = fmod(fqn[i] * t + phn[i], 2*M_PI);
    ae[i] = fmod(fqe[i] * t + phe[i], 2*M_PI);
    ai[i] = fmod(fqi[i] * t + phi[i], 2*M_PI);
  }
  elem[0*6+0] = 4.44352267
              - cos(an[0]      - an[1] * 3. + an[2] * 2.) * 3.492e-5
              + cos(an[0] * 2. - an[1] * 6. + an[2] * 4.) * 8.47e-6
              + cos(an[0] * 3. - an[1] * 9. + an[2] * 6.) * 1.31e-6
              - cos(an[0]      - an[1]                     ) * 5.228e-5
              - cos(an[0] * 2. - an[1] * 2.                ) * 1.3665e-4;
  elem[0*6+1] = 
                sin(an[0]      - an[1] * 3. + an[2] * 2.) * .02547217
              - sin(an[0] * 2. - an[1] * 6. + an[2] * 4.) * .00308831
              - sin(an[0] * 3. - an[1] * 9. + an[2] * 6.) * 3.181e-4
              - sin(an[0] * 4. - an[1] * 12 + an[2] * 8.) * 3.749e-5
              - sin(an[0]      - an[1]                     ) * 5.785e-5
              - sin(an[0] * 2. - an[1] * 2.                ) * 6.232e-5
              - sin(an[0] * 3. - an[1] * 3.                ) * 2.795e-5
              + t * 4.44519055 - .23805158;
  elem[0*6+2] = cos(ae[0]) * .00131238
              + cos(ae[1]) * 7.181e-5
              + cos(ae[2]) * 6.977e-5
              + cos(ae[3]) * 6.75e-6
              + cos(ae[4]) * 6.27e-6
              + cos(an[0]) * 1.941e-4
              - cos(-an[0]      + an[1] * 2.) * 1.2331e-4
              + cos(an[0] * -2. + an[1] * 3.) *  3.952e-5;
  elem[0*6+3] = sin(ae[0]) * .00131238
              + sin(ae[1]) * 7.181e-5
              + sin(ae[2]) * 6.977e-5
              + sin(ae[3]) * 6.75e-6
              + sin(ae[4]) * 6.27e-6
              + sin(an[0]) * 1.941e-4
              - sin(-an[0]      + an[1] * 2.) * 1.2331e-4
              + sin(an[0] * -2. + an[1] * 3.) * 3.952e-5;
  elem[0*6+4] = cos(ai[0]) * .03787171
              + cos(ai[1]) * 2.701e-5
              + cos(ai[2]) * 3.076e-5
              + cos(ai[3]) * 1.218e-5
              + cos(ai[4]) * 5.37e-6;
  elem[0*6+5] = sin(ai[0]) * .03787171
              + sin(ai[1]) * 2.701e-5
              + sin(ai[2]) * 3.076e-5
              + sin(ai[3]) * 1.218e-5
              + sin(ai[4]) * 5.37e-6;
  elem[1*6+0] = 2.49254257
              + cos(an[0] - an[1] * 3. + an[2] * 2.) * 2.55e-6
              - cos(           an[1]      - an[2]     ) * 4.216e-5
              - cos(           an[1] * 2. - an[2] * 2.) * 1.0256e-4;
  elem[1*6+1] = 
              - sin(an[0]      - an[1] * 3. + an[2] * 2.) * .0018605
              + sin(an[0] * 2. - an[1] * 6. + an[2] * 4.) * 2.1999e-4
              + sin(an[0] * 3. - an[1] * 9. + an[2] * 6.) * 2.31e-5
              + sin(an[0] * 4. - an[1] * 12 + an[2] * 8.) * 4.3e-6
              - sin(                an[1]      - an[2]     ) * 9.011e-5
              - sin(                an[1] * 2. - an[2] * 2.) * 9.107e-5
              - sin(                an[1] * 3. - an[2] * 3.) * 4.275e-5
              - sin(                an[1] * 2.     - an[3] * 2.) * 1.649e-5
              + t * 2.49295252 + 3.09804641;
  elem[1*6+2] = cos(ae[0]) * -3.35e-6
              + cos(ae[1]) * .00118763
              + cos(ae[2]) * 8.6159e-4
              + cos(ae[3]) * 7.15e-5
              + cos(ae[4]) * 5.559e-5
              - cos(-an[1] + an[2] * 2.) * 8.46e-5
              + cos(an[1] * -2. + an[2] * 3.) * 9.181e-5
              + cos(-an[1] + an[3] * 2.) * 2.003e-5
              + cos(an[1]) * 8.977e-5;
  elem[1*6+3] = sin(ae[0]) * -3.35e-6
              + sin(ae[1]) * .00118763
              + sin(ae[2]) * 8.6159e-4
              + sin(ae[3]) * 7.15e-5
              + sin(ae[4]) * 5.559e-5
              - sin(-an[1] + an[2] * 2.) * 8.46e-5
              + sin(an[1] * -2. + an[2] * 3.) * 9.181e-5
              + sin(-an[1] + an[3] * 2.) * 2.003e-5
              + sin(an[1]) * 8.977e-5;
  elem[1*6+4] = cos(ai[0]) * -1.2175e-4
              + cos(ai[1]) * 3.5825e-4
              + cos(ai[2]) * 2.9008e-4
              + cos(ai[3]) * 9.778e-5
              + cos(ai[4]) * 3.397e-5;
  elem[1*6+5] = sin(ai[0]) * -1.2175e-4
              + sin(ai[1]) * 3.5825e-4
              + sin(ai[2]) * 2.9008e-4
              + sin(ai[3]) * 9.778e-5
              + sin(ai[4]) * 3.397e-5;
  elem[2*6+0] = 1.5159549
              + cos(an[2] - an[3] * 2. + ae[2]) * 9.74e-6
              - cos(an[1] - an[2]) * 1.06e-4
              + cos(an[1] * 2. - an[2] * 2.) * 5.416e-5
              - cos(an[2] - an[3]) * 2.359e-5
              - cos(an[2] * 2. - an[3] * 2.) * 7.07e-5
              - cos(an[2] * 3. - an[3] * 3.) * 3.628e-5;
  elem[2*6+1] = 
                sin(an[0] - an[1] * 3. + an[2] * 2.) * 6.6057e-4
              - sin(an[0] * 2. - an[1] * 6. + an[2] * 4.) * 7.651e-5
              - sin(an[0] * 3. - an[1] * 9. + an[2] * 6.) * 8.96e-6
              - sin(an[0] * 4. - an[1] * 12. + an[2] * 8.) * 2.53e-6
              - sin(an[2] - an[3] * 4. + an[4] * 3.) * 5.291e-5
              - sin(an[2] - an[3] * 2. + ae[4]) * 7.34e-6
              - sin(an[2] - an[3] * 2. + ae[3]) * 1.83e-6
              + sin(an[2] - an[3] * 2. + ae[2]) * 1.4791e-4
              + sin(an[2] - an[3] * 2. + ae[1]) * -7.77e-6
              + sin(an[1] - an[2]) * 9.776e-5
              + sin(an[1] * 2. - an[2] * 2.) * 7.313e-5
              + sin(an[1] * 3. - an[2] * 3.) * 3.471e-5
              + sin(an[1] * 4. - an[2] * 4.) * 1.889e-5
              - sin(an[2] - an[3]) * 6.789e-5 
              - sin(an[2] * 2. - an[3] * 2.) * 8.286e-5
              + sin(an[2] * 3. - an[3] * 3.) * -3.381e-5
              - sin(an[2] * 4. - an[3] * 4.) * 1.579e-5
              - sin(an[2] - an[4]) * 1.021e-5
              - sin(an[2] * 2. - an[4] * 2.) * 1.708e-5
              + t * 1.51614811 + 2.28540169;
  elem[2*6+2] = cos(ae[0]) * -2.1e-7
              - cos(ae[1]) * 2.2795e-4
              + cos(ae[2]) * .00390469
              + cos(ae[3]) * 3.0917e-4
              + cos(ae[4]) * 2.2192e-4
              + cos(an[1]) * 2.934e-5
              + cos(an[2]) * 2.62e-5
              + cos(-an[1] + an[2] * 2.) * 5.119e-5
              - cos(an[1] * -2. + an[2] * 3.) * 1.0386e-4
              - cos(an[1] * -3. + an[2] * 4.) * 2.716e-5
              + cos(an[3]) * -1.622e-5
              + cos(-an[2] + an[3] * 2.) * 5.4923e-4
              + cos(an[2] * -2. + an[3] * 3.) * 3.47e-5
              + cos(an[2] * -3. + an[3] * 4.) * 1.281e-5
              + cos(-an[2] + an[4] * 2.) * 2.181e-5
              + cos(an[2]) * 4.625e-5;
  elem[2*6+3] = sin(ae[0]) * -2.1e-7
              - sin(ae[1]) * 2.2795e-4
              + sin(ae[2]) * .00390469
              + sin(ae[3]) * 3.0917e-4
              + sin(ae[4]) * 2.2192e-4
              + sin(an[1]) * 2.934e-5
              + sin(an[2]) * 2.62e-5
              + sin(-an[1] + an[2] * 2.) * 5.119e-5
              - sin(an[1] * -2. + an[2] * 3.) * 1.0386e-4
              - sin(an[1] * -3. + an[2] * 4.) * 2.716e-5
              + sin(an[3]) * -1.622e-5
              + sin(-an[2] + an[3] * 2.) * 5.4923e-4
              + sin(an[2] * -2. + an[3] * 3.) * 3.47e-5
              + sin(an[2] * -3. + an[3] * 4.) * 1.281e-5
              + sin(-an[2] + an[4] * 2.) * 2.181e-5
              + sin(an[2]) * 4.625e-5;
  elem[2*6+4] = cos(ai[0]) * -1.086e-5
              - cos(ai[1]) * 8.151e-5
              + cos(ai[2]) * .00111336
              + cos(ai[3]) * 3.5014e-4
              + cos(ai[4]) * 1.065e-4;
  elem[2*6+5] = sin(ai[0]) * -1.086e-5
              - sin(ai[1]) * 8.151e-5
              + sin(ai[2]) * .00111336
              + sin(ai[3]) * 3.5014e-4
              + sin(ai[4]) * 1.065e-4;
  elem[3*6+0] = .72166316
              - cos(an[2] - an[3] * 2. + ae[2]) * 2.64e-6
              - cos(an[3] * 2. - an[4] * 3. + ae[4]) * 2.16e-6
              + cos(an[3] * 2. - an[4] * 3. + ae[3]) * 6.45e-6
              - cos(an[3] * 2. - an[4] * 3. + ae[2]) * 1.11e-6
              + cos(an[1] - an[3]) * -6.223e-5
              - cos(an[2] - an[3]) * 5.613e-5
              - cos(an[3] - an[4]) * 3.994e-5
              - cos(an[3] * 2. - an[4] * 2.) * 9.185e-5
              - cos(an[3] * 3. - an[4] * 3.) * 5.831e-5
              - cos(an[3] * 4. - an[4] * 4.) * 3.86e-5
              - cos(an[3] * 5. - an[4] * 5.) * 2.618e-5
              - cos(an[3] * 6. - an[4] * 6.) * 1.806e-5;
  elem[3*6+1] = 
                sin(an[2] - an[3] * 4. + an[4] * 3.) * 2.061e-5
              - sin(an[2] - an[3] * 2. + ae[4]) * 2.07e-6
              - sin(an[2] - an[3] * 2. + ae[3]) * 2.88e-6
              - sin(an[2] - an[3] * 2. + ae[2]) * 4.079e-5
              + sin(an[2] - an[3] * 2. + ae[1]) * 2.11e-6
              - sin(an[3] * 2. - an[4] * 3. + ae[4]) * 5.183e-5
              + sin(an[3] * 2. - an[4] * 3. + ae[3]) * 1.5987e-4
              + sin(an[3] * 2. - an[4] * 3. + ae[2]) * -3.505e-5
              - sin(an[3] * 3. - an[4] * 4. + ae[4]) * 1.56e-6
              + sin(an[1] - an[3]) * 4.054e-5
              + sin(an[2] - an[3]) * 4.617e-5
              - sin(an[3] - an[4]) * 3.1776e-4
              - sin(an[3] * 2. - an[4] * 2.) * 3.0559e-4
              - sin(an[3] * 3. - an[4] * 3.) * 1.4836e-4
              - sin(an[3] * 4. - an[4] * 4.) * 8.292e-5
              + sin(an[3] * 5. - an[4] * 5.) * -4.998e-5
              - sin(an[3] * 6. - an[4] * 6.) * 3.156e-5
              - sin(an[3] * 7. - an[4] * 7.) * 2.056e-5
              - sin(an[3] * 8. - an[4] * 8.) * 1.369e-5
              + t * .72171851 + .85635879;
  elem[3*6+2] = cos(ae[0]) * -2e-8
              - cos(ae[1]) * 1.29e-6
              - cos(ae[2]) * 3.2451e-4
              + cos(ae[3]) * 9.3281e-4
              + cos(ae[4]) * .00112089
              + cos(an[1]) * 3.386e-5
              + cos(an[3]) * 1.746e-5
              + cos(-an[1] + an[3] * 2.) * 1.658e-5
              + cos(an[2]) * 2.889e-5
              - cos(-an[2] + an[3] * 2.) * 3.586e-5
              + cos(an[3]) * -1.786e-5
              - cos(an[4]) * 3.21e-5
              - cos(-an[3] + an[4] * 2.) * 1.7783e-4
              + cos(an[3] * -2. + an[4] * 3.) * 7.9343e-4
              + cos(an[3] * -3. + an[4] * 4.) * 9.948e-5
              + cos(an[3] * -4. + an[4] * 5.) * 4.483e-5
              + cos(an[3] * -5. + an[4] * 6.) * 2.513e-5
              + cos(an[3] * -6. + an[4] * 7.) * 1.543e-5;
  elem[3*6+3] = sin(ae[0]) * -2e-8
              - sin(ae[1]) * 1.29e-6
              - sin(ae[2]) * 3.2451e-4
              + sin(ae[3]) * 9.3281e-4
              + sin(ae[4]) * .00112089
              + sin(an[1]) * 3.386e-5
              + sin(an[3]) * 1.746e-5
              + sin(-an[1] + an[3] * 2.) * 1.658e-5
              + sin(an[2]) * 2.889e-5
              - sin(-an[2] + an[3] * 2.) * 3.586e-5
              + sin(an[3]) * -1.786e-5
              - sin(an[4]) * 3.21e-5
              - sin(-an[3] + an[4] * 2.) * 1.7783e-4
              + sin(an[3] * -2. + an[4] * 3.) * 7.9343e-4
              + sin(an[3] * -3. + an[4] * 4.) * 9.948e-5
              + sin(an[3] * -4. + an[4] * 5.) * 4.483e-5
              + sin(an[3] * -5. + an[4] * 6.) * 2.513e-5
              + sin(an[3] * -6. + an[4] * 7.) * 1.543e-5;
  elem[3*6+4] = cos(ai[0]) * -1.43e-6
              - cos(ai[1]) * 1.06e-6
              - cos(ai[2]) * 1.4013e-4
              + cos(ai[3]) * 6.8572e-4
              + cos(ai[4]) * 3.7832e-4;
  elem[3*6+5] = sin(ai[0]) * -1.43e-6
              - sin(ai[1]) * 1.06e-6
              - sin(ai[2]) * 1.4013e-4
              + sin(ai[3]) * 6.8572e-4
              + sin(ai[4]) * 3.7832e-4;
  elem[4*6+0] = .46658054
              + cos(an[3] * 2. - an[4] * 3. + ae[4]) * 2.08e-6
              - cos(an[3] * 2. - an[4] * 3. + ae[3]) * 6.22e-6
              + cos(an[3] * 2. - an[4] * 3. + ae[2]) * 1.07e-6
              - cos(an[1] - an[4]) * 4.31e-5
              + cos(an[2] - an[4]) * -3.894e-5
              - cos(an[3] - an[4]) * 8.011e-5
              + cos(an[3] * 2. - an[4] * 2.) * 5.906e-5
              + cos(an[3] * 3. - an[4] * 3.) * 3.749e-5
              + cos(an[3] * 4. - an[4] * 4.) * 2.482e-5
              + cos(an[3] * 5. - an[4] * 5.) * 1.684e-5;
  elem[4*6+1] =
              - sin(an[2] - an[3] * 4. + an[4] * 3.) * 7.82e-6
              + sin(an[3] * 2. - an[4] * 3. + ae[4]) * 5.129e-5
              - sin(an[3] * 2. - an[4] * 3. + ae[3]) * 1.5824e-4
              + sin(an[3] * 2. - an[4] * 3. + ae[2]) * 3.451e-5
              + sin(an[1] - an[4]) * 4.751e-5
              + sin(an[2] - an[4]) * 3.896e-5
              + sin(an[3] - an[4]) * 3.5973e-4
              + sin(an[3] * 2. - an[4] * 2.) * 2.8278e-4
              + sin(an[3] * 3. - an[4] * 3.) * 1.386e-4
              + sin(an[3] * 4. - an[4] * 4.) * 7.803e-5
              + sin(an[3] * 5. - an[4] * 5.) * 4.729e-5
              + sin(an[3] * 6. - an[4] * 6.) * 3e-5
              + sin(an[3] * 7. - an[4] * 7.) * 1.962e-5
              + sin(an[3] * 8. - an[4] * 8.) * 1.311e-5
              + t * .46669212 - .9155918;
  elem[4*6+2] = cos(ae[1]) * -3.5e-7
              + cos(ae[2]) * 7.453e-5
              - cos(ae[3]) * 7.5868e-4
              + cos(ae[4]) * .00139734
              + cos(an[1]) * 3.9e-5
              + cos(-an[1] + an[4] * 2.) * 1.766e-5
              + cos(an[2]) * 3.242e-5
              + cos(an[3]) * 7.975e-5
              + cos(an[4]) * 7.566e-5
              + cos(-an[3] + an[4] * 2.) * 1.3404e-4
              - cos(an[3] * -2. + an[4] * 3.) * 9.8726e-4
              - cos(an[3] * -3. + an[4] * 4.) * 1.2609e-4
              - cos(an[3] * -4. + an[4] * 5.) * 5.742e-5
              - cos(an[3] * -5. + an[4] * 6.) * 3.241e-5 
              - cos(an[3] * -6. + an[4] * 7.) * 1.999e-5
              - cos(an[3] * -7. + an[4] * 8.) * 1.294e-5;
  elem[4*6+3] = sin(ae[1]) * -3.5e-7
              + sin(ae[2]) * 7.453e-5
              - sin(ae[3]) * 7.5868e-4
              + sin(ae[4]) * .00139734
              + sin(an[1]) * 3.9e-5
              + sin(-an[1] + an[4] * 2.) * 1.766e-5
              + sin(an[2]) * 3.242e-5
              + sin(an[3]) * 7.975e-5
              + sin(an[4]) * 7.566e-5
              + sin(-an[3] + an[4] * 2.) * 1.3404e-4
              - sin(an[3] * -2. + an[4] * 3.) * 9.8726e-4
              - sin(an[3] * -3. + an[4] * 4.) * 1.2609e-4
              - sin(an[3] * -4. + an[4] * 5.) * 5.742e-5
              - sin(an[3] * -5. + an[4] * 6.) * 3.241e-5
              - sin(an[3] * -6. + an[4] * 7.) * 1.999e-5
              - sin(an[3] * -7. + an[4] * 8.) * 1.294e-5;
  elem[4*6+4] = cos(ai[0]) * -4.4e-7
              - cos(ai[1]) * 3.1e-7
              + cos(ai[2]) * 3.689e-5
              - cos(ai[3]) * 5.9633e-4
              + cos(ai[4]) * 4.5169e-4;
  elem[4*6+5] = sin(ai[0]) * -4.4e-7
              - sin(ai[1]) * 3.1e-7
              + sin(ai[2]) * 3.689e-5
              - sin(ai[3]) * 5.9633e-4
              + sin(ai[4]) * 4.5169e-4;
}

static
const double gust86_rmu[5] = {
   1.291892353675174e-08,
   1.291910570526396e-08,
   1.291910102284198e-08,
   1.291942656265575e-08,
   1.291935967091320e-08};

/*
const double GUST86toJ2000[9] = {
   9.753205572598290957e-01, 6.194437810676107434e-02, 2.119261772583629030e-01,
  -2.207428547845518695e-01, 2.529905336992995280e-01, 9.419492459363773150e-01,
   4.733143558215848563e-03,-9.654836528287313313e-01, 2.604206471702025216e-01
};
*/
const double GUST86toVsop87[9] = {
   9.753206632086812015e-01, 6.194425668001473004e-02, 2.119257251551559653e-01,
  -2.006444610981783542e-01,-1.519328516640849367e-01, 9.678110398294910731e-01,
   9.214881523275189928e-02,-9.864478281437795399e-01,-1.357544776485127136e-01
};

#define GUST86_DIM (5*6)
static double t_0 = -1e100;
static double t_1 = -1e100;
static double t_2 = -1e100;
static double gust86_elem_0[GUST86_DIM];
static double gust86_elem_1[GUST86_DIM];
static double gust86_elem_2[GUST86_DIM];
/* 1 day: */
#define DELTA_T 1.0

static double gust86_jd0 = -1e100;
static double gust86_elem[GUST86_DIM];

void GetGust86Coor(double jd,int body,double *xyz) {
  GetGust86OsculatingCoor(jd,jd,body,xyz);
}

void GetGust86OsculatingCoor(const double jd0,const double jd,
                             const int body,double *xyz) {
  double x[3];
  if (jd0 != gust86_jd0) {
    const double t0 = jd0 - 2444239.5;
    gust86_jd0 = jd0;
    CalcInterpolatedElements(t0,gust86_elem,
                             GUST86_DIM,
                             &CalcGust86Elem,DELTA_T,
                             &t_0,gust86_elem_0,
                             &t_1,gust86_elem_1,
                             &t_2,gust86_elem_2);
/*
    printf("GetGust86Coor(%d): %f %f  %f %f  %f %f\n",
           body,
           gust86_elem[body*6+0],gust86_elem[body*6+1],gust86_elem[body*6+2],
           gust86_elem[body*6+3],gust86_elem[body*6+4],gust86_elem[body*6+5]);
*/
  }
  EllipticToRectangularN(gust86_rmu[body],gust86_elem+(body*6),jd-jd0,x);
  xyz[0] = GUST86toVsop87[0]*x[0]+GUST86toVsop87[1]*x[1]+GUST86toVsop87[2]*x[2];
  xyz[1] = GUST86toVsop87[3]*x[0]+GUST86toVsop87[4]*x[1]+GUST86toVsop87[5]*x[2];
  xyz[2] = GUST86toVsop87[6]*x[0]+GUST86toVsop87[7]*x[1]+GUST86toVsop87[8]*x[2];
}