local bool subdivp(nodeptr n)
{
cellptr SAFE q = TC(n);
SUBV(dr, PosC(q), pos0); /* compute displacement */
DOTVP(drsq, dr, dr); /* and find dist squared */
qmem = q; /* remember we know them */
return (drsq < Rcrit2(q)); /* apply standard rule */
}
char* showCell(const NBodyCell* c)
{
char* buf;
char* posBuf;
if (!c)
return NULL;
posBuf = showVector(Pos(c));
if (0 > asprintf(&buf,
"NBodyCell = {\n"
" cellnode = {\n"
" pos = %s\n"
" next = %p\n"
" mass = %f\n"
" type = %d\n"
" }\n"
" rcrit2 = %f\n"
" more = %p\n"
" stuff = {\n"
" .quad = {\n"
" .xx = %f, .xy = %f, .xz = %f,\n"
" .yy = %f, .yz = %f,\n"
" .zz = %f\n"
" },\n"
"\n"
" .subp = {\n"
" %p, %p, %p, %p,\n"
" %p, %p, %p, %p\n"
" }\n"
" }\n"
"}\n",
posBuf,
(void*) Next(c),
Mass(c),
Type(c),
Rcrit2(c),
(void*) More(c),
Quad(c).xx, Quad(c).xy, Quad(c).xz,
Quad(c).yy, Quad(c).yz,
Quad(c).zz,
(void*) Subp(c)[0], (void*) Subp(c)[1], (void*) Subp(c)[2], (void*) Subp(c)[3],
(void*) Subp(c)[5], (void*) Subp(c)[5], (void*) Subp(c)[6], (void*) Subp(c)[7]
))
{
mw_fail("asprintf() failed\n");
}
free(posBuf);
return buf;
}
local bool accept(nodeptr c, real psize, vector pmid)
{
real dmax, dsq, dk;
int k;
dmax = psize; /* init maximum distance */
dsq = 0.0; /* and squared min distance */
for (k = 0; k < NDIM; k++) { /* loop over space dims */
dk = Pos(c)[k] - pmid[k]; /* form distance to midpnt */
if (dk < 0) /* and get absolute value */
dk = - dk;
if (dk > dmax) /* keep track of max value */
dmax = dk;
dk -= ((real) 0.5) * psize; /* allow for size of cell */
if (dk > 0)
dsq += dk * dk; /* sum min dist to cell ^2 */
}
return (dsq > Rcrit2(c) && /* test angular criterion */
dmax > ((real) 1.5) * psize); /* and adjacency criterion */
}
local bool accept(nodeptr c, real psize, vector pmid)
{
real dmax, dsq, dk;
int k;
dmax = psize; // init maximum distance
dsq = 0.0; // and squared min distance
for (k = 0; k < NDIM; k++) { // loop over space dims
dk = Pos(c)[k] - pmid[k]; // form distance to midpnt
if (dk < 0) // and get absolute value
dk = - dk;
if (dk > dmax) // keep track of max value
dmax = dk;
dk -= ((real) 0.5) * psize; // allow for size of cell
if (dk > 0)
dsq += dk * dk; // sum (min dist to cell)^2
}
return (dsq > Rcrit2(c) && // test angular criterion
dmax > ((real) 1.5) * psize); // and adjacency criterion
}
/*
* nbodyGravity: Walk the tree starting at the root to do force
* calculations.
*
*
* Random notes:
* - Not inlined without inline from multiple calls in
* mapForceBody(). Measurably better with the inline, but only
* slightly.
*/
static inline mwvector nbGravity(const NBodyCtx* ctx, NBodyState* st, const Body* p)
{
mwbool skipSelf = FALSE;
mwvector pos0 = Pos(p);
mwvector acc0 = ZERO_VECTOR;
const NBodyNode* q = (const NBodyNode*) st->tree.root; /* Start at the root */
while (q != NULL) /* while not at end of scan */
{
mwvector dr = mw_subv(Pos(q), pos0); /* Then compute distance */
real drSq = mw_sqrv(dr); /* and distance squared */
if (isBody(q) || (drSq >= Rcrit2(q))) /* If is a body or far enough away to approximate */
{
if (mw_likely((const Body*) q != p)) /* self-interaction? */
{
real drab, phii, mor3;
/* Compute gravity */
drSq += ctx->eps2; /* use standard softening */
drab = mw_sqrt(drSq);
phii = Mass(q) / drab;
mor3 = phii / drSq;
acc0.x += mor3 * dr.x;
acc0.y += mor3 * dr.y;
acc0.z += mor3 * dr.z;
if (ctx->useQuad && isCell(q)) /* if cell, add quad term */
{
real dr5inv, drQdr, phiQ;
mwvector Qdr;
/* form Q * dr */
Qdr.x = Quad(q).xx * dr.x + Quad(q).xy * dr.y + Quad(q).xz * dr.z;
Qdr.y = Quad(q).xy * dr.x + Quad(q).yy * dr.y + Quad(q).yz * dr.z;
Qdr.z = Quad(q).xz * dr.x + Quad(q).yz * dr.y + Quad(q).zz * dr.z;
/* form dr * Q * dr */
drQdr = Qdr.x * dr.x + Qdr.y * dr.y + Qdr.z * dr.z;
dr5inv = 1.0 / (sqr(drSq) * drab); /* form dr^-5 */
/* get quad. part of phi */
phiQ = 2.5 * (dr5inv * drQdr) / drSq;
acc0.x += phiQ * dr.x;
acc0.y += phiQ * dr.y;
acc0.z += phiQ * dr.z;
/* acceleration */
acc0.x -= dr5inv * Qdr.x;
acc0.y -= dr5inv * Qdr.y;
acc0.z -= dr5inv * Qdr.z;
}
}
else
{
skipSelf = TRUE; /* Encountered self */
}
q = Next(q); /* Follow next link */
}
else
{
q = More(q); /* Follow to the next level if need to go deeper */
}
}
if (!skipSelf)
{
/* If a body does not encounter itself in its traversal of the
* tree, it is "tree incest" */
nbReportTreeIncest(ctx, st);
}
return acc0;
}
