void planet::get_eph(const epoch& when, array3D &r, array3D &v) const{
if(when.mjd2000() != cached_epoch.mjd2000() || cached_epoch.mjd2000() == 0) {
double elements[6];
std::copy(keplerian_elements.begin(), keplerian_elements.end(), elements);
double dt = (when.mjd2000() - ref_mjd2000) * ASTRO_DAY2SEC;
elements[5] += mean_motion * dt;
elements[5] = m2e(elements[5],elements[1]);
par2ic(elements, mu_central_body, cached_r, cached_v);
cached_epoch = when;
}
r = cached_r;
v = cached_v;
}
void keplerian::eph_impl(double mjd2000, array3D &r, array3D &v) const {
double dt = (mjd2000 - m_ref_mjd2000) * ASTRO_DAY2SEC;
if (m_keplerian_elements[1] > 1e-3 && m_keplerian_elements[2] > 1e-3)
{
double elements[6];
std::copy(m_keplerian_elements.begin(), m_keplerian_elements.end(), elements);
elements[5] += m_mean_motion * dt;
elements[5] = m2e(elements[5],elements[1]);
par2ic(elements, get_mu_central_body(), r, v);
} else { // Small inclinations and eccentricities (including nans), we use lagrangian propagation
r = m_r;
v = m_v;
propagate_lagrangian(r, v, dt, get_mu_central_body());
}
}
/// Computes the low-precision ephemerides
void jpl_lp::eph_impl(double mjd2000, array3D &r, array3D &v) const {
if (mjd2000 <=-73048.0 || mjd2000>=18263.0) {
throw_value_error("Ephemeris are out of range [1800-2050]");
}
// algorithm from http://ssd.jpl.nasa.gov/txt/p_elem_t1.txt downloded 2013
array6D elements, elements2;
double dt = (mjd2000 - ref_mjd2000) / 36525.0; // Number of centuries passed since J2000.0
for(unsigned int i= 0;i<6;++i) {
elements[i] = (jpl_elements[i] + jpl_elements_dot[i] * dt);
}
elements2[0] = elements[0] * ASTRO_AU;
elements2[1] = elements[1];
elements2[2] = elements[2] * ASTRO_DEG2RAD;
elements2[3] = elements[5] * ASTRO_DEG2RAD;
elements2[4] = (elements[4] - elements[5]) * ASTRO_DEG2RAD;
elements2[5] = (elements[3] - elements[4]) * ASTRO_DEG2RAD;
elements2[5] = m2e(elements2[5],elements2[1]);
par2ic(elements2, get_mu_central_body(), r, v);
}
