local real gdisk(real rad)
{
real x;
x = 0.5 * alpha * rad;
return - alpha*alpha * mdisk * x *
(bessi0(x) * bessk0(x) - bessi1(x) * bessk1(x));
}
static double plazmaWidth_integrand(double Pcm)
{ int err;
double E1,E2,sqrt_s;
if(Pcm==0) return 0;
E1=sqrt(Pcm*Pcm+plazmaWidth_m[0]*plazmaWidth_m[0]);
E2=sqrt(Pcm*Pcm+plazmaWidth_m[1]*plazmaWidth_m[1]);
sqrt_s=E1+E2;
if(sqrt_s<=plazmaWidth_m[2]+plazmaWidth_m[3]) return 0;
return 4*bessk1(sqrt_s/plazmaWidth_T)*cs22(plazmaWidth_cc,1,Pcm, -1., 1. , &err)*pow(sqrt_s*Pcm,3.)/E1/E2;
}
void potential_double(int *ndim,double *pos,double *acc,double *pot,double *time)
{
double apar, qpar, spar, ppar, lpar, rpar, rcyl;
int i;
// 20070312 bwillett added ppar - the plummer denominator: r + rc = sqrt(x^2+y^2+z^2) + rc
// 20070312 bwillett added lpar - the logarithmic argument: R^2 + (z/q)^2 + d^2
// 20070427 bwillett added rpar - the spherical radius: r + rc - rc = ppar - plu_rc
// 20070501 bwillett added apar - a + qpar
// 20070507 bwillett took out pow statements
// 20070507 bwillett used hypot from math.h
rcyl = hypot(pos[X],pos[Y]);
ppar = sqrt ((pos[X]*pos[X])+(pos[Y]*pos[Y])+(pos[Z]*pos[Z])) + plu_rc;
rpar = ppar - plu_rc;
lpar = (rcyl*rcyl) + ((pos[Z]/q)*(pos[Z]/q)) + (d*d);
// This is only valid for 3 dimensions, and is in (x,y,z)
// Recall F_mu = -grad_mu U
// So a_mu = -grad_mu Phi
// I did these derivatives in Mathematica, and will try to keep it consistent with the conventions written above
acc[X] = - ( ( (2.0*vhalo*vhalo*pos[X])/(lpar) ) + ( (plu_mass*pos[X])/(rpar*ppar*ppar) ) );
acc[Y] = - ( ( (2.0*vhalo*vhalo*pos[Y])/(lpar) ) + ( (plu_mass*pos[Y])/(rpar*ppar*ppar) ) );
acc[Z] = - ( ( (2.0*vhalo*vhalo*pos[Z])/(lpar) ) + ( (plu_mass*pos[Z])/(rpar*ppar*ppar) ) );
// Copied from expdisk.c
double r2, r, arg, i0, k0, i1, k1, f;
double alpha;
alpha = 1.0/a;
r = rpar;
r2 = r*r;
arg = 0.5*alpha*r;
//printf("%f %f %f %f %f\n", a, mass, r, r2, x);
i0=bessi0(arg);
k0=bessk0(arg);
i1=bessi1(arg);
k1=bessk1(arg);
// 20080928 - willeb added exponential disk to acceleration field
*pot = -mass*arg*(i0*k1-i1*k0);
f = -0.5*alpha*alpha*alpha*mass*(i0*k0-i1*k1);
acc[X] += f*pos[X];
acc[Y] += f*pos[Y];
acc[Z] += f*pos[Z];
// 20080928 - willeb added bulge and halo to potential
*pot += (-(plu_mass)/ppar);
*pot += (vhalo*vhalo*log(lpar));
}
float bessk(int n, float x)
{
float bessk0(float x);
float bessk1(float x);
void nrerror(char error_text[]);
int j;
float bk,bkm,bkp,tox;
if (n < 2) nrerror("Index n less than 2 in bessk");
tox=2.0/x;
bkm=bessk0(x);
bk=bessk1(x);
for (j=1;j<n;j++) {
bkp=bkm+j*tox*bk;
bkm=bk;
bk=bkp;
}
return bk;
}
