void potential_double(int *ndim,double *pos,double *acc,double *pot,double *time)
{
double theta, sintheta, costheta, xi, mu, f1val, f2val, quant, psi;
costheta = pos[Z] / sqrt(pos[X]*pos[X] + pos[Y]*pos[Y] + pos[Z]*pos[Z]);
if(pos[Z] >= 0) {
theta = acos(costheta);
sintheta = cos(PI/2.0 - theta);
} else {
theta = -acos(costheta);
sintheta = cos(PI/2.0 - theta);
}
psi = atan2(pos[Y],pos[X]);
xi = sqrt(pos[X]*pos[X] + pos[Y]*pos[Y] + pos[Z]*pos[Z])/a;
quant = 1.0 + xi*xi;
mu = (2.0*xi*sintheta)/quant;
// Calculate the integrals
f1val = f1(mu);
f2val = f2(mu);
// The energy (FIX THIS, it doesn't matter unless you want to separate out parts of the tail)
*pot = ((-G*ringmass)/(2*PI)) * fenergy(pos[X],pos[Y],pos[Z],a);
// The accelerations
double accmag;
accmag = (-G*ringmass / (PI*a*a)) * (xi*sintheta*pow(quant, -1.5)*f1val - pow(quant, -1.5)*f2val);
acc[X] = accmag*cos(psi);
acc[Y] = accmag*sin(psi);
acc[Z] = (-G*ringmass / (PI*a*a)) * (xi*costheta*pow(quant, -1.5)*f1val);
}
inline double fpower(double f) const {
return fenergy(f)/(double)Signal::size;
}
