static private void vp(List <Body> bv, int nstep)
{
MathVector dacc = MathVector.makeMathVector();
MathVector dvel = MathVector.makeMathVector();
double dthf = 0.5 * BH.DTIME;
for (int i = 0; i < bv.Count; ++i)
{
Body b = bv[i];
MathVector acc1 = b.newAcc.cloneMathVector();
if (nstep > 0)
{
dacc.subtraction2(acc1, b.acc);
dvel.multScalar2(dacc, dthf);
dvel.addition(b.vel);
b.vel = dvel.cloneMathVector();
}
b.acc = acc1.cloneMathVector();
dvel.multScalar2(b.acc, dthf);
MathVector vel1 = b.vel.cloneMathVector();
vel1.addition(dvel);
MathVector dpos = vel1.cloneMathVector();
dpos.multScalar1(BH.DTIME);
dpos.addition(b.pos);
b.pos = dpos.cloneMathVector();
vel1.addition(dvel);
b.vel = vel1.cloneMathVector();
}
}
/**
* Descend tree finding center of mass coordinates
*
* @return the mass of this node
*/
public override double hackcofm()
{
double mq = 0.0;
MathVector tmpPos = MathVector.makeMathVector();
MathVector tmpv = MathVector.makeMathVector();
for (int i = 0; i < NSUB; i++)
{
Node r = this.subp[i];
if (r != null)
{
double mr = r.hackcofm();
mq = mr + mq;
tmpv.multScalar2(r.pos, mr);
tmpPos.addition(tmpv);
}
}
mass = mq;
pos = tmpPos;
pos.divScalar(mass);
return(mq);
}
