inline
void update_density(particle_t* pi, particle_t* pj, float h2, float C, float* i_rho, float* j_rho) {
float r2 = vec3_dist2(pi->x, pj->x);
float z = h2 - r2;
if (z > 0) {
float rho_ij = C * z * z * z;
*i_rho += rho_ij;
*j_rho += rho_ij;
}
}
*
* The formula for density is
* \[
* \rho_i = \sum_j m_j W_{p6}(r_i-r_j,h)
* = \frac{315 m}{64 \pi h^9} \sum_{j \in N_i} (h^2 - r^2)^3.
* \]
* We search for neighbors of node $i$ by checking every particle,
* which is not very efficient. We do at least take advange of
* the symmetry of the update ($i$ contributes to $j$ in the same
* way that $j$ contributes to $i$).
*@c*/
inline
void update_density(particle_t* restrict pi, particle_t* restrict pj, float h2, float C)
{
float r2 = vec3_dist2(pi->x, pj->x);
float z = h2-r2;
if (z > 0) {
float rho_ij = C*z*z*z;
pi->rho += rho_ij;
//pj->rho += rho_ij;
}
}
void compute_density(sim_state_t* restrict s, sim_param_t* restrict params)
{
int n = s->n;
particle_t* p = s->part;
hash_bin_t* hash = s->hash;
