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grav.c
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grav.c
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#include <stdio.h>
#include <math.h>
#include "kd.h"
#include "grav.h"
void kdCellPot(KD kd,PINIT *p,int n,int iSoftType,double *pdPot)
{
int i,j;
float x,y,z,dx,dy,dz,d2,twoh,dir;
for (i=0;i<n;++i) pdPot[i] = 0.0;
for (i=0;i<(n-1);++i) {
x = p[i].r[0];
y = p[i].r[1];
z = p[i].r[2];
for (j=i+1;j<n;++j) {
dx = x - p[j].r[0];
dy = y - p[j].r[1];
dz = z - p[j].r[2];
d2 = dx*dx + dy*dy + dz*dz;
twoh = p[i].fSoft + p[j].fSoft;
switch (iSoftType) {
case PLUMMER:
dir = 1.0/sqrt(d2 + 0.25*twoh*twoh);
break;
default:
case SPLINE:
SPLINE_POT(d2,twoh,dir);
}
pdPot[i] += kd->G*p[j].fMass*dir;
pdPot[j] += kd->G*p[i].fMass*dir;
}
}
}
void kdSubPot(KD kd,PINIT *p,int n,PINIT *ps,int iSoftType,double *pdPot)
{
int i;
float dx,dy,dz,d2,twoh,dir;
for (i=0;i<n;++i) {
dx = ps->r[0] - p[i].r[0];
dy = ps->r[1] - p[i].r[1];
dz = ps->r[2] - p[i].r[2];
d2 = dx*dx + dy*dy + dz*dz;
twoh = ps->fSoft + p[i].fSoft;
switch (iSoftType) {
case PLUMMER:
dir = 1.0/sqrt(d2 + 0.25*twoh*twoh);
break;
default:
case SPLINE:
SPLINE_POT(d2,twoh,dir);
}
pdPot[i] -= kd->G*ps->fMass*dir;
}
}
void kdAddScoopPot(KD kd,PINIT *pGroup,int n,float *ri,float fScoop,float *rel,
int iSoftType,double *pdPot)
{
KDN *c;
PINIT *p;
int pj,cp,i;
float dx,dy,dz,x,y,z,lx,ly,lz,sx,sy,sz,fDist2,fBall2,nx,ny,nz;
float d2,twoh,dir;
c = kd->kdNodes;
if (!c) return;
p = kd->pInit;
lx = kd->fPeriod[0];
ly = kd->fPeriod[1];
lz = kd->fPeriod[2];
x = ri[0];
y = ri[1];
z = ri[2];
fBall2 = fScoop*fScoop;
cp = ROOT;
while (1) {
INTERSECT(c,cp,fBall2,lx,ly,lz,x,y,z,sx,sy,sz);
/*
** We have an intersection to test.
*/
if (c[cp].iDim >= 0) {
cp = LOWER(cp);
continue;
}
else {
for (pj=c[cp].pLower;pj<=c[cp].pUpper;++pj) {
dx = sx - p[pj].r[0];
dy = sy - p[pj].r[1];
dz = sz - p[pj].r[2];
fDist2 = dx*dx + dy*dy + dz*dz;
if (fDist2 < fBall2) {
/*
** Add this particle's potential to all the particles in
** pGroup.
*/
nx = p[pj].r[0] - rel[0];
ny = p[pj].r[1] - rel[1];
nz = p[pj].r[2] - rel[2];
if (nx > 0.5*lx) nx -= lx;
if (nx <= -0.5*lx) nx += lx;
if (ny > 0.5*ly) ny -= ly;
if (ny <= -0.5*ly) ny += ly;
if (nz > 0.5*lz) nz -= lz;
if (nz <= -0.5*lz) nz += lz;
for (i=0;i<n;++i) {
dx = nx - pGroup[i].r[0];
dy = ny - pGroup[i].r[1];
dz = nz - pGroup[i].r[2];
d2 = dx*dx + dy*dy + dz*dz;
twoh = p[pj].fSoft + pGroup[i].fSoft;
switch (iSoftType) {
case PLUMMER:
dir = 1.0/sqrt(d2 + 0.25*twoh*twoh);
break;
default:
case SPLINE:
SPLINE_POT(d2,twoh,dir);
}
pdPot[i] += kd->G*p[pj].fMass*dir;
}
}
}
}
GetNextCell:
SETNEXT(cp);
if (cp == ROOT) break;
}
}