double OctTree_t::EvaluatePotential(const HBTReal targetPos[3], const HBTReal targetMass)
/*return specific physical potential, GM/Rphysical.
* targetPos[] is comoving.
* if targetMass!=0, then the self-potential from targetMass is excluded.
* do not set targetMass (i.e., keep to 0.) if target is outside the particlelist of tree*/
{
OctTreeCell_t *nop = 0;
HBTInt no;
double r2, dx, dy, dz, mass, r, u, h, h_inv, wp;
double pot, pos_x, pos_y, pos_z;
pos_x = targetPos[0];
pos_y = targetPos[1];
pos_z = targetPos[2];
h = 2.8 * HBTConfig.SofteningHalo;
h_inv = 1.0 / h;
pot=targetMass/HBTConfig.SofteningHalo; //to cancle out the self-potential added during tree walk.
no = NumberOfParticles;//start from root node
while(no >= 0)
{
if(no < NumberOfParticles) /* single particle */
{
dx = Snapshot->GetComovingPosition(no)[0] - pos_x;
dy = Snapshot->GetComovingPosition(no)[1] - pos_y;
dz = Snapshot->GetComovingPosition(no)[2] - pos_z;
if(HBTConfig.PeriodicBoundaryOn)
{
dx=NEAREST(dx);
dy=NEAREST(dy);
dz=NEAREST(dz);
}
mass = Snapshot->GetMass(no);
no = NextnodeFromParticle[no];
r2 = dx * dx + dy * dy + dz * dz;
}
else
{
nop = &Nodes[no];
dx = nop->way.s[0] - pos_x;
dy = nop->way.s[1] - pos_y;
dz = nop->way.s[2] - pos_z;
if(HBTConfig.PeriodicBoundaryOn)
{
dx=NEAREST(dx);
dy=NEAREST(dy);
dz=NEAREST(dz);
}
mass = nop->way.mass;
r2 = dx * dx + dy * dy + dz * dz;
/* we have an internal node. Need to check opening criterion */
if((nop->way.len * nop->way.len )>( r2 * HBTConfig.TreeNodeOpenAngleSquare))
{
/* open cell */
no = nop->way.nextnode;
continue;
}
no = nop->way.sibling; /* node can be used */
}
r = sqrt(r2);
if(r >= h)
pot -= mass / r;
else
{
u = r * h_inv;
if(u < 0.5)
wp = -2.8 + u * u * (5.333333333333 + u * u * (6.4 * u - 9.6));
else
wp =
-3.2 + 0.066666666667 / u + u * u * (10.666666666667 +
u * (-16.0 + u * (9.6 - 2.133333333333 * u)));
pot += mass * h_inv * wp;
}
}
return pot*PhysicalConst::G/Snapshot->ScaleFactor;
}
HBTInt treesearch_infect_particles(HBTInt seed, HBTInt grpid,
struct ParticleGroup *GrpTags, HBTReal PPos[][3])
{
/*tag all the particles that are linked to seed with grpid
* Note if system stack size is too small, this recursive routine may crash
* in that case you should set: ulimit -s unlimited (bash) before running.
**/
HBTInt numngb, totnumngb, no, p;
double dx, dy, dz, r2, h2;
union NODE *this;
HBTReal *searchcenter;
searchcenter=PPos[GrpTags[seed].PIndex];
//~ h2 = radius * radius;
numngb = 0;
no = NumPart;
while(no >= 0)//infect neighbours
{
if(no < NumPart) /* single particle */
{
*pInfected = no;
no = Nextnode[*pInfected];
if(GrpTags[*pInfected].GrpID>=0) //already tagged
continue;
p = GrpTags[*pInfected].PIndex;
dx = PPos[p][0] - searchcenter[0];
#ifdef PERIODIC_BDR
dx=NEAREST(dx);
#endif
if(dx < -LinkLength)
continue;
if(dx > LinkLength)
continue;
dy =PPos[p][1] - searchcenter[1];
#ifdef PERIODIC_BDR
dy=NEAREST(dy);
#endif
if(dy < -LinkLength)
continue;
if(dy > LinkLength)
continue;
dz = PPos[p][2] - searchcenter[2];
#ifdef PERIODIC_BDR
dz=NEAREST(dz);
#endif
if(dz < -LinkLength)
continue;
if(dz > LinkLength)
continue;
r2 = dx * dx + dy * dy + dz * dz;
if(r2 < LinkLength2) //confirm the infection (fill the stack)
{
GrpTags[*pInfected].GrpID=grpid;
numngb++;
pInfected++;
}
}
else
{
this = &Nodes[no];
no = Nodes[no].way.sibling; /* in case the node can be discarded */
//since way.s[3] is CoM rather than center of cube,compare with Len rather than Lenhalf to allow for misaligned CoM
if((NEAREST(this->way.s[0] - searchcenter[0]) + this->way.len) < -LinkLength)
continue;
if((NEAREST(this->way.s[0] - searchcenter[0]) - this->way.len) > LinkLength)
continue;
if((NEAREST(this->way.s[1] - searchcenter[1]) + this->way.len) < -LinkLength)
continue;
if((NEAREST(this->way.s[1] - searchcenter[1]) - this->way.len) > LinkLength)
continue;
if((NEAREST(this->way.s[2] - searchcenter[2]) + this->way.len) < -LinkLength)
continue;
if((NEAREST(this->way.s[2] - searchcenter[2]) - this->way.len) > LinkLength)
continue;
no = this->way.nextnode; /* ok, we need to open the node */
}
}
//~ printf("ngb=%d ",numngb);
totnumngb=numngb;
while(numngb>0)//pop the stack
{
pInfected--;
totnumngb+=treesearch_infect_particles(*pInfected,grpid, GrpTags, PPos);
numngb--;
}
return totnumngb; //total number of infected particles (excluding the seed particle)
}
int ngb_treefind_variable(float searchcenter[3], float hguess)
{
int numngb, no, p;
double dx, dy, dz, r2, h2;
struct NODE *this;
h2 = hguess * hguess;
numngb = 0;
no = NumPart;
while(no >= 0)
{
if(no < NumPart) /* single particle */
{
p = no;
no = Nextnode[no];
dx = NEAREST(P[p].Pos[0] - searchcenter[0]);
if(dx < -hguess)
continue;
if(dx > hguess)
continue;
dy = NEAREST(P[p].Pos[1] - searchcenter[1]);
if(dy < -hguess)
continue;
if(dy > hguess)
continue;
dz = NEAREST(P[p].Pos[2] - searchcenter[2]);
if(dz < -hguess)
continue;
if(dz > hguess)
continue;
r2 = dx * dx + dy * dy + dz * dz;
if(r2 < h2)
{
R2list[numngb].r2 = r2;
R2list[numngb].index = p;
numngb++;
}
}
else
{
this = &Nodes[no];
no = Nodes[no].u.d.sibling; /* in case the node can be discarded */
if((NEAREST(this->center[0] - searchcenter[0]) + 0.5 * this->len) < -hguess)
continue;
if((NEAREST(this->center[0] - searchcenter[0]) - 0.5 * this->len) > hguess)
continue;
if((NEAREST(this->center[1] - searchcenter[1]) + 0.5 * this->len) < -hguess)
continue;
if((NEAREST(this->center[1] - searchcenter[1]) - 0.5 * this->len) > hguess)
continue;
if((NEAREST(this->center[2] - searchcenter[2]) + 0.5 * this->len) < -hguess)
continue;
if((NEAREST(this->center[2] - searchcenter[2]) - 0.5 * this->len) > hguess)
continue;
no = this->u.d.nextnode; /* ok, we need to open the node */
}
}
/*
printf("numngb=%d\n", numngb);
*/
return numngb;
}
HBTInt treesearch_sphere(HBTReal searchcenter[3], HBTReal radius,HBTInt *PIndex,HBTReal PPos[][3])
{/*find a list of particles from PIndex within radius around searchcenter
* return the number of neighbors
* also store distance^2 and ID in the global variables NgbR2 and NgbID */
HBTInt numngb, no, p;
double dx, dy, dz, r2, h2;
union NODE *this;
h2 = radius * radius;
numngb = 0;
no = NumPart;
while(no >= 0)
{
if(no < NumPart) /* single particle */
{
p = PIndex[no];
no = Nextnode[no];
dx = PPos[p][0] - searchcenter[0];
#ifdef PERIODIC_BDR
dx=NEAREST(dx);
#endif
if(dx < -radius)
continue;
if(dx > radius)
continue;
dy =PPos[p][1] - searchcenter[1];
#ifdef PERIODIC_BDR
dy=NEAREST(dy);
#endif
if(dy < -radius)
continue;
if(dy > radius)
continue;
dz = PPos[p][2] - searchcenter[2];
#ifdef PERIODIC_BDR
dz=NEAREST(dz);
#endif
if(dz < -radius)
continue;
if(dz > radius)
continue;
r2 = dx * dx + dy * dy + dz * dz;
if(r2 < h2)
{
NgbR2[numngb]= r2;
NgbID[numngb]= p;
numngb++;
if(numngb==NgbNMax)
{
NgbNMax*=2;
NgbR2=realloc(NgbR2,sizeof(HBTReal)*NgbNMax);
NgbID=realloc(NgbID,sizeof(HBTInt)*NgbNMax);
}
}
}
else
{
this = &Nodes[no];
no = Nodes[no].way.sibling; /* in case the node can be discarded */
//since way.s[3] is CoM rather than center of cube,compare with Len rather than Lenhalf to allow for misaligned CoM
if((NEAREST(this->way.s[0] - searchcenter[0]) + this->way.len) < -radius)
continue;
if((NEAREST(this->way.s[0] - searchcenter[0]) - this->way.len) > radius)
continue;
if((NEAREST(this->way.s[1] - searchcenter[1]) + this->way.len) < -radius)
continue;
if((NEAREST(this->way.s[1] - searchcenter[1]) - this->way.len) > radius)
continue;
if((NEAREST(this->way.s[2] - searchcenter[2]) + this->way.len) < -radius)
continue;
if((NEAREST(this->way.s[2] - searchcenter[2]) - this->way.len) > radius)
continue;
no = this->way.nextnode; /* ok, we need to open the node */
}
}
/*
fprintf(Logfile,"numngb=%d\n", numngb);
*/
return numngb;
}
