char *swi_get_fict_name(int32 ipl, char *snam) { if(read_elements_file(ipl, 0, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, snam, NULL, NULL) == ERR) strcpy(snam, "name not found"); return snam; }
/* computes a planet from osculating elements * * tjd julian day * ipl body number * ipli body number in planetary data structure * iflag flags */ int swi_osc_el_plan(double tjd, double *xp, int ipl, int ipli, double *xearth, double *xsun, char *serr) { double pqr[9], x[6]; double eps, K, fac, rho, cose, sine; double alpha, beta, zeta, sigma, M2, Msgn, M_180_or_0; double tjd0, tequ, mano, sema, ecce, parg, node, incl, dmot; double cosnode, sinnode, cosincl, sinincl, cosparg, sinparg; double M, E; struct plan_data *pedp = &swed.pldat[SEI_EARTH]; struct plan_data *pdp = &swed.pldat[ipli]; int32 fict_ifl = 0; int i; /* orbital elements, either from file or, if file not found, * from above built-in set */ if (read_elements_file(ipl, tjd, &tjd0, &tequ, &mano, &sema, &ecce, &parg, &node, &incl, NULL, &fict_ifl, serr) == ERR) return ERR; dmot = 0.9856076686 * DEGTORAD / sema / sqrt(sema); /* daily motion */ if (fict_ifl & FICT_GEO) dmot /= sqrt(SUN_EARTH_MRAT); cosnode = cos(node); sinnode = sin(node); cosincl = cos(incl); sinincl = sin(incl); cosparg = cos(parg); sinparg = sin(parg); /* Gaussian vector */ pqr[0] = cosparg * cosnode - sinparg * cosincl * sinnode; pqr[1] = -sinparg * cosnode - cosparg * cosincl * sinnode; pqr[2] = sinincl * sinnode; pqr[3] = cosparg * sinnode + sinparg * cosincl * cosnode; pqr[4] = -sinparg * sinnode + cosparg * cosincl * cosnode; pqr[5] = -sinincl * cosnode; pqr[6] = sinparg * sinincl; pqr[7] = cosparg * sinincl; pqr[8] = cosincl; /* Kepler problem */ E = M = swi_mod2PI(mano + (tjd - tjd0) * dmot); /* mean anomaly of date */ /* better E for very high eccentricity and small M */ if (ecce > 0.975) { M2 = M * RADTODEG; if (M2 > 150 && M2 < 210) { M2 -= 180; M_180_or_0 = 180; } else M_180_or_0 = 0; if (M2 > 330) M2 -= 360; if (M2 < 0) { M2 = -M2; Msgn = -1; } else Msgn = 1; if (M2 < 30) { M2 *= DEGTORAD; alpha = (1 - ecce) / (4 * ecce + 0.5); beta = M2 / (8 * ecce + 1); zeta = pow(beta + sqrt(beta * beta + alpha * alpha), 1/3); sigma = zeta - alpha / 2; sigma = sigma - 0.078 * sigma * sigma * sigma * sigma * sigma / (1 + ecce); E = Msgn * (M2 + ecce * (3 * sigma - 4 * sigma * sigma * sigma)) + M_180_or_0; } } E = swi_kepler(E, M, ecce); /* position and speed, referred to orbital plane */ if (fict_ifl & FICT_GEO) K = KGAUSS_GEO / sqrt(sema); else K = KGAUSS / sqrt(sema); cose = cos(E); sine = sin(E); fac = sqrt((1 - ecce) * (1 + ecce)); rho = 1 - ecce * cose; x[0] = sema * (cose - ecce); x[1] = sema * fac * sine; x[3] = -K * sine / rho; x[4] = K * fac * cose / rho; /* transformation to ecliptic */ xp[0] = pqr[0] * x[0] + pqr[1] * x[1]; xp[1] = pqr[3] * x[0] + pqr[4] * x[1]; xp[2] = pqr[6] * x[0] + pqr[7] * x[1]; xp[3] = pqr[0] * x[3] + pqr[1] * x[4]; xp[4] = pqr[3] * x[3] + pqr[4] * x[4]; xp[5] = pqr[6] * x[3] + pqr[7] * x[4]; /* transformation to equator */ eps = swi_epsiln(tequ); swi_coortrf(xp, xp, -eps); swi_coortrf(xp+3, xp+3, -eps); /* precess to J2000 */ if (tequ != J2000) { swi_precess(xp, tequ, J_TO_J2000); swi_precess(xp+3, tequ, J_TO_J2000); } /* to solar system barycentre */ if (fict_ifl & FICT_GEO) { for (i = 0; i <= 5; i++) { xp[i] += xearth[i]; } } else { for (i = 0; i <= 5; i++) { xp[i] += xsun[i]; } } if (pdp->x == xp) { pdp->teval = tjd; /* for precession! */ pdp->iephe = pedp->iephe; } return OK; }