// Iterative method to calculate new X and Z values for the specified time of flight
static inline void CalcXandZ(double &X, double &Z, const VECTOR3 Pos, const VECTOR3 Vel,
double a, const double Time, const double SqrtMu)
{
const double MAX_ITERS = 10;
double C, S, T, dTdX, DeltaTime, r = Mag(Pos), IterNum = 0;
// These don't change over the iterations
double RVMu = (Pos * Vel) / SqrtMu; // Dot product of position and velocity divided
// by the squareroot of Mu
double OneRA = (1 - (r / a)); // One minus Pos over the semi-major axis
C = CalcC(Z);
S = CalcS(Z);
T = ((RVMu * pow(X, 2) * C) + (OneRA * pow(X, 3) * S) + (r * X)) / SqrtMu;
DeltaTime = Time - T;
// Iterate while the result isn't within tolerances
while (fabs(DeltaTime) > EPSILON && IterNum++ < MAX_ITERS) {
dTdX = ((pow(X, 2) * C) + (RVMu * X * (1 - Z * S)) + (r * (1 - Z * C))) / SqrtMu;
X = X + (DeltaTime / dTdX);
Z = CalcZ(X, a);
C = CalcC(Z);
S = CalcS(Z);
T = ((RVMu * pow(X, 2) * C) + (OneRA * pow(X, 3) * S) + (r * X)) / SqrtMu;
DeltaTime = Time - T;
}
}
// Given the specified position and velocity vectors for a given orbit, retuns the position
// and velocity vectors after a specified time
void PredictPosVelVectors(const VECTOR3 &Pos, const VECTOR3 &Vel, double a, double Mu,
double Time, VECTOR3 &NewPos, VECTOR3 &NewVel, double &NewVelMag)
{
double SqrtMu = sqrt(Mu);
// Variables for computation
double X = (SqrtMu * Time) / a; // Initial guesses for X
double Z = CalcZ(X, a); // and Z
double C, S; // C(Z) and S(Z)
double F, FDot, G, GDot;
// Calculate the X and Z for the specified time of flight
CalcXandZ(X, Z, Pos, Vel, a, Time, SqrtMu);
// Calculate C(Z) and S(Z)
C = CalcC(Z);
S = CalcS(Z);
// Calculate the new position and velocity vectors
F = CalcF(X, C, Mag(Pos));
G = CalcG(Time, X, S, SqrtMu);
NewPos = (Pos * F) + (Vel * G);
FDot = CalcFDot(SqrtMu, Mag(Pos), Mag(NewPos), X, Z, S);
GDot = CalcGDot(X, C, Mag(NewPos));
NewVel = (Pos * FDot) + (Vel * GDot);
NewVelMag = Mag(NewVel);
}
ribi::PlaneZ::Coordinats2D ribi::PlaneZ::CalcProjection(
const Coordinats3D& points
) const
{
assert(points.size() >= 3);
const double x_origin = 0.0;
const double y_origin = 0.0;
const double z_origin = CalcZ(x_origin,y_origin);
Coordinats2D v;
for (const auto& point: points)
{
const Double x(boost::geometry::get<0>(point));
const Double y(boost::geometry::get<1>(point));
const Double z(boost::geometry::get<2>(point));
const Double dx =
sqrt( //Apfloat does not add the std::
((x - x_origin) * (x - x_origin))
+ ((z - z_origin) * (z - z_origin))
) * (x - x_origin)
;
const Double dy =
sqrt( //Apfloat does not add the std::
((y - y_origin) * (y - y_origin))
+ ((z - z_origin) * (z - z_origin))
) * (y - y_origin)
;
Coordinat2D point_xy(dx,dy);
v.push_back(point_xy);
}
return v;
}
double ribi::PlaneZ::CalcError(const Coordinat3D& coordinat) const noexcept
{
const double x = boost::geometry::get<0>(coordinat);
const double y = boost::geometry::get<1>(coordinat);
const double z = boost::geometry::get<2>(coordinat);
const double expected{z};
const double calculated{CalcZ(x,y)};
const double error{std::abs(calculated - expected)};
return error;
}
double CalcR(double (*y)(double), double a, double b)
{
double z = CalcZ(y,a,b);
double w = CalcW(y,a,b);
return a+(b-a)*(z-derevative(y,a)+w)/(derevative(y,b)-derevative(y,a)+2*w);
}
double CalcW(double (*y)(double), double a, double b)
{
double z = CalcZ(y,a,b);
return sqrt(z*z - derevative(y,a)*derevative(y,b));
}
void SmallFlowStep(ConfigData *config) {
// Here we have to implement the RK scheme from 1006.4518 [hep-lat]
// Appendix C
// W_0 = V_t
// W_1 = exp(1/4 Z_0) W_0
// W_2 = exp(8/9 Z_1 - 17/36 Z_0) W_1
// W_t+eps = exp(3/4 Z_2 - 8/9 Z_1 + 17/36 Z_0) W_2
//
// Z_i = eps Z(W_i)
//
// The input configuration 'config' will be overwritten with the
// configuration at flow time t'=t+eps.
// We allocate a new ConfigData
// W_0 = V_t : W0 = config;
ConfigData *S0 = new ConfigData(opt.ns, opt.ns, opt.ns, opt.nt, 3);
// W_1 = exp(1/4 Z_0) W_0
ConfigData *W1 = new ConfigData(opt.ns, opt.ns, opt.ns, opt.nt, 3);
#pragma omp parallel for
for (int x=0; x<opt.ns*opt.ns*opt.ns*opt.nt; x++) {
std::complex<double> U[3][3], Z0[3][3], A[3][3], expA[3][3], newU[3][3];
for (int mu=0; mu<4; mu++) {
// For link U_x,mu
CalcZ(Z0, config, x, mu);
S0->replace(*Z0, x, mu); // save this into ConfigData for Z0s
za(A, 1.0/4.0*opt.eps, Z0);
expM(expA, A);
config->extract(*U, x, mu);
axb(newU, expA, U);
#ifdef DEBUG
if (testUnitarity(newU) > 1e-5) {
std::cout << "WARNING: New link in SmallFlowStep() not unitary anymore!" << std::endl;
}
#endif
W1->replace(*newU, x, mu);
}
}
// W_2 = exp(8/9 Z_1 - 17/36 Z_0) W_1
ConfigData *W2 = new ConfigData(opt.ns, opt.ns, opt.ns, opt.nt, 3);
#pragma omp parallel for
for (int x=0; x<opt.ns*opt.ns*opt.ns*opt.nt; x++) {
std::complex<double> U[3][3], Z0[3][3], Z1[3][3], A[3][3], A2[3][3], expA[3][3], newU[3][3];
for (int mu=0; mu<4; mu++) {
// First part with Z0
S0->extract(*Z0, x, mu); // get this from ConfigData for Z0s
za(A, -17.0/36.0*opt.eps, Z0);
// Add second part with Z1
CalcZ(Z1, W1, x, mu);
za(A2, 8.0/9.0*opt.eps, Z1);
// Add both parts
apb(A,A2);
S0->replace(*A, x, mu); // save this into ConfigData S0 (A=-17/36*Z0 + 8/9*Z1)
expM(expA, A);
W1->extract(*U, x, mu);
axb(newU, expA, U);
#ifdef DEBUG
if (testUnitarity(newU) > 1e-5) {
std::cout << "WARNING: New link in SmallFlowStep() not unitary anymore!" << std::endl;
}
#endif
W2->replace(*newU, x, mu);
}
}
delete W1; W1 = 0;
// W_t+eps = exp(3/4 Z_2 - 8/9 Z_1 + 17/36 Z_0) W_2
#pragma omp parallel for
for (int x=0; x<opt.ns*opt.ns*opt.ns*opt.nt; x++) {
std::complex<double> U[3][3], Z0[3][3], Z2[3][3], A[3][3], A2[3][3], expA[3][3], newU[3][3];
for (int mu=0; mu<4; mu++) {
// For link U_x,mu
// First part with Z0 and Z1
S0->extract(*Z0, x, mu); // load -17/36*Z0 + 8/9*Z1
za(A, -1.0, Z0); // switch the sign
// Add third part with Z2
CalcZ(Z2, W2, x, mu);
za(A2, 3.0/4.0*opt.eps, Z2);
// Add both parts
apb(A,A2);
expM(expA, A);
W2->extract(*U, x, mu);
axb(newU, expA, U);
#ifdef DEBUG
if (testUnitarity(newU) > 1e-5) {
std::cout << "WARNING: New link in SmallFlowStep() not unitary anymore!" << std::endl;
}
#endif
config->replace(*newU, x, mu);
}
}
// Cleaning up
delete W2; W2 = 0;
delete S0; S0 = 0;
}
