void rk4(float *r, float *vr, float *J2, float *rp, float *cm, int N, float dt, float tend)
{
float kr[4], kv[4];
float r0, v0, r1;
for (int i = 0; i<N; ++i)
{
float t = 0;
while (t < tend)
{
r0 = r[i];
v0 = vr[i];
/* Step 1 */
r1 = r0;
kr[0] = v0 ;
kv[0] = compute_acc(r1, J2[i], rp, cm, N);
/* Step 2 */
r1 = r0 + 0.5*dt*kr[0];
kr[1] = v0 + 0.5*dt*kv[0];
kv[1] = compute_acc(r1, J2[i], rp, cm, N);
/* Step 3 */
r1 = r0 + 0.5*dt*kr[1];
kr[2] = v0 + 0.5*dt*kv[1];
kv[2] = compute_acc(r1, J2[i], rp, cm, N);
/* Step 4 */
r1 = r0 + dt*kr[2];
kr[3] = v0 + dt*kv[2];
kv[3] = compute_acc(r1, J2[i], rp, cm, N);
r[i] = r0 + dt*(kr[0] + 2.0*kr[1] + 2.0*kr[2] + kr[3])/6.0;
vr[i] = v0 + dt*(kv[0] + 2.0*kv[1] + 2.0*kv[2] + kv[3])/6.0;
t+=dt;
}
}
}
static void trs_prepare_acc(struct tr_score *sc)
{
double acc = sc->origin->conf->acc;
if (acc < 0)
acc = 0;
else if (acc > MAX_ACC)
acc = MAX_ACC;
sc->great = sc->origin->great;
sc->good = sc->origin->good;
sc->miss = sc->origin->miss;
sc->acc = compute_acc(sc->great, sc->good, sc->miss);
while (sc->acc > acc) {
double try = compute_acc(sc->great-1, sc->good+1, sc->miss);
if (try <= acc) {
sc->great--;
sc->good++;
sc->acc = try;
} else {
sc->great--;
sc->miss++;
sc->acc = compute_acc(sc->great, sc->good, sc->miss);
}
}
static void trs_prepare_ggm(struct tr_score *sc)
{
int good = sc->origin->conf->good;
int miss = sc->origin->conf->miss;
if (good < 0)
good = 0;
if (miss < 0)
miss = 0;
// Remove exceeding good and miss
while (good + miss > sc->origin->great) {
if (good > 0)
good--;
else
miss--;
}
sc->great = sc->origin->great - good - miss;
sc->good = good;
sc->miss = miss;
sc->acc = compute_acc(sc->great, sc->good, sc->miss);
}
