V6
fk524(V6 v)
{
v = m6v6(M, v);
/* restore e-terms */
#ifdef ETERMS
{
double m; /* modulus of position vector */
V3 s0;
V3 s1, s1dot;
V3 r0, r0dot;
V3 r1, r1dot;
/* cache the modulus */
m = v6mod(v);
/* convert the state vector back to a unit vector */
v6GetPos(v) = v3scale(v6GetPos(v), 1/m);
v6GetVel(v) = v3scale(v6GetVel(v), CB/(m*as2r(1)));
/* now proceed with the standard treatment */
r1 = v6GetPos(v);
r1dot = v6GetVel(v);
s1 = v3unit(r1);
s0 = s1;
r0 = v3sum(s1, v3diff(A, v3scale(s0, v3dot(s0, A))));
#ifdef ETERMS_ITERATE
s0 = v3unit(r0);
r0 = v3sum(s1, v3diff(A, v3scale(s0, v3dot(s0, A))));
#endif
v6SetPos(v, r0);
#ifdef ETERMS_VEL
s1dot = v3scale(r1dot, 1/v3mod(r1));
r0dot = v3sum(s1dot, v3diff(Adot, v3scale(s0, v3dot(s0, Adot))));
v6SetVel(v, r0dot);
#endif
/* convert the unit vector back into a state vector */
v6GetPos(v) = v3scale(v6GetPos(v), m);
v6GetVel(v) = v3scale(v6GetVel(v), (m*as2r(1))/CB);
}
#endif
return(v);
}
V6
ldeflect(V6 s, V6 e, int flag)
{
double cprime;
double g1;
double g2;
V3 ehat;
V3 p;
V3 qhat;
V3 x; /* the deflection vector */
V3 x1; /* scratch */
V3 x2; /* scratch */
p = v6GetPos(s);
{
V6 v6;
v6 = v6sum(e, s);
qhat = v3unit(v6GetPos(v6));
}
ehat = v3unit(v6GetPos(e));
cprime = 86400.0 * (IAU_C / IAU_AU);
g1 = (2.0 * IAU_K * IAU_K) / (cprime * cprime * v6mod(e));
g2 = 1 + v3dot(qhat, ehat);
/* limit the value of g2 as Patrick Wallace does:
** clip it at 1.0e-5 radians (~922 arcseconds)
*/
if (g2 < 1.0e-5) {
g2 = 1.0e-5;
}
x1 = v3scale(ehat, v3dot(p, qhat));
x2 = v3scale(qhat, v3dot(p, ehat));
x = v3scale(v3diff(x1, x2), g1/g2);
if (flag > 0) {
p = v3sum(p, x);
} else if (flag < 0) {
p = v3diff(p, x);
}
v6SetPos(s, p);
return(s);
}
