void reb_move_to_com(struct reb_simulation* const r){
const int N = r->N;
struct reb_particle* restrict const particles = r->particles;
struct reb_particle com = reb_get_com(r);
for (int i=0;i<N;i++){
particles[i].x -= com.x;
particles[i].y -= com.y;
particles[i].z -= com.z;
particles[i].vx -= com.vx;
particles[i].vy -= com.vy;
particles[i].vz -= com.vz;
}
}
void rebx_modify_orbits_forces(struct reb_simulation* const sim, struct rebx_effect* const effect){
const struct rebx_params_modify_orbits_forces* const params = effect->paramsPtr;
const int N_real = sim->N - sim->N_var;
struct reb_particle com;
switch(params->coordinates){
case JACOBI:
com = reb_get_jacobi_com(&sim->particles[N_real-1]); // We start with outermost particle, so get its jacobi COM
break;
case BARYCENTRIC:
com = reb_get_com(sim); // COM of whole system
break;
case HELIOCENTRIC:
com = sim->particles[0]; // Use the central body as the reference
break;
default:
fprintf(stderr, "coordinates in parameters for modify_orbits_forces are not supported.\n");
exit(1);
}
struct reb_particle* p0 = &sim->particles[0];
for(int i=N_real-1;i>0;--i){
struct reb_particle* p = &sim->particles[i];
double tau_a = rebx_get_param_double(p, "tau_a");
double tau_e = rebx_get_param_double(p, "tau_e");
double tau_inc = rebx_get_param_double(p, "tau_inc");
if(isnan(tau_a)){
rebx_set_param_double(p, "tau_a", INFINITY);
tau_a = INFINITY;
}
if(isnan(tau_e)){
rebx_set_param_double(p, "tau_e", INFINITY);
tau_e = INFINITY;
}
if(isnan(tau_inc)){
rebx_set_param_double(p, "tau_inc", INFINITY);
tau_inc = INFINITY;
}
const double dvx = p->vx - com.vx;
const double dvy = p->vy - com.vy;
const double dvz = p->vz - com.vz;
double ax = 0.;
double ay = 0.;
double az = 0.;
ax = dvx/(2.*tau_a);
ay = dvy/(2.*tau_a);
az = dvz/(2.*tau_a);
if (tau_e < INFINITY || tau_inc < INFINITY){ // need h and e vectors for both types
const double dx = p->x-com.x;
const double dy = p->y-com.y;
const double dz = p->z-com.z;
const double r = sqrt ( dx*dx + dy*dy + dz*dz );
const double vr = (dx*dvx + dy*dvy + dz*dvz)/r;
const double prefac = 2*vr/r;
ax += prefac*dx/tau_e;
ay += prefac*dy/tau_e;
az += prefac*dz/tau_e + 2.*dvz/tau_inc;
}
p->ax += ax;
p->ay += ay;
p->az += az;
p0->ax -= p->m/p0->m*ax; // add back reactions onto central body
p0->ay -= p->m/p0->m*ay;
p0->az -= p->m/p0->m*az;
if(params->coordinates == JACOBI){
rebxtools_update_com_without_particle(&com, p);
}
}
}
