// Runge-Kutta 4 algorithm
void System::RK4(){
vec2dN K1(nObj), K2(nObj), K3(nObj), K4(nObj);
vec2dN L1(nObj), L2(nObj), L3(nObj), L4(nObj);
vec2dN NewR(nObj), NewV(nObj);
if (nObj == 1){ // If only ONE object
K1 = h*derX(vec2dN(nObj));
L1 = h*(SunInf(vec2dN(nObj)));
K2 = h*derX(L1*0.5);
L2 = h*(SunInf(K1*0.5));
K3 = h*derX(L2*0.5);
L3 = h*(SunInf(K2*0.5));
K4 = h*derX(L3);
L4 = h*(SunInf(K3));
} else { // If more than one object
if (!statSun){ // Sun mobile or not pressent
K1 = h*derX(vec2dN(nObj));
L1 = h*derV(vec2dN(nObj));
K2 = h*derX(L1*0.5);
L2 = h*derV(K1*0.5);
K3 = h*derX(L2*0.5);
L3 = h*derV(L2*0.5);
K4 = h*derX(L3);
L4 = h*derV(K4);
} else { // If the sun is stationary
K1 = h*derX(vec2dN(nObj));
L1 = h*(derV(vec2dN(nObj)) + SunInf(vec2dN(nObj)));
K2 = h*derX(L1*0.5);
L2 = h*(derV(K1*0.5) + SunInf(K1*0.5));
K3 = h*derX(L2*0.5);
L3 = h*(derV(K2*0.5) + SunInf(K2*0.5));
K4 = h*derX(L3);
L4 = h*(derV(K3) + SunInf(K3));
}
}
for (int i = 0 ; i < nObj ; i++){
NewR[i] = sys[i].relR + (K1[i] + 2*K2[i] + 2*K3[i] + K4[i])/(double)6;
NewV[i] = sys[i].relV + (L1[i] + 2*L2[i] + 2*L3[i] + L4[i])/(double)6;
}
calc_potential();
for (int i = 0 ; i < nObj ; i++){
sys[i].update(NewR[i], NewV[i], sys[i].relT+h);
}
}
void visitFieldRef(FieldRef *Ref) {
// The real magic happens here
Field *F = Ref->getField();
if (F != TheField) {
// This is a reference to a field we are not processing.
return;
}
// Only adjust if this is not the first update (in time order)
if (LastTS) {
// We're in the last time-step, check if there is a write to
// this field before us.
std::list<Field*>::const_iterator Curr = std::find(UpdateOrder.begin(),
UpdateOrder.end(),
Func->getOutput());
assert(Curr != UpdateOrder.end() && "Field not in update list");
bool Found = false;
for (std::list<Field*>::const_iterator I = UpdateOrder.begin();
I != Curr; ++I) {
const Field *O = *I;
if (O == TheField) {
Found = true;
break;
}
}
if (!Found) {
// We are in the last time-step and there is no previous update,
// so do not count this field.
return;
}
}
unsigned NumDims = InRegion.getNumDimensions();
Region NewR(NumDims);
const std::vector<IntConstant*> &Offsets = Ref->getOffsets();
#if 0
llvm::errs() << "Visiting " << Ref->getField()->getName() << "[";
for (unsigned i = 0, e = Offsets.size(); i != e; ++i) {
if (i != 0) llvm::errs() << "][";
llvm::errs() << Offsets[i]->getValue();
}
llvm::errs() << "]\n";
llvm::errs() << "FRegion In: ";
FRegion.dump(llvm::errs());
llvm::errs() << "\n";
llvm::errs() << "InRegion In: ";
InRegion.dump(llvm::errs());
llvm::errs() << "\n";
#endif
for (unsigned i = 0; i < NumDims; ++i) {
std::pair<int, unsigned> InBound = InRegion.getBound(i);
std::pair<int, unsigned> FBound = FRegion.getBound(i);
int Off = Offsets[i]->getValue();
if (InBound.first + Off < FBound.first) {
// We need more elements on the lower bound
int Diff = FBound.first - (InBound.first + Off);
FBound.first -= Diff;
FBound.second += Diff;
}
if (InBound.first + InBound.second + Off > FBound.first + FBound.second) {
// We need more elements on the upper bound
int Diff = InBound.first + InBound.second + Off -
(FBound.first + FBound.second);
FBound.second += Diff;
}
#if 0
llvm::errs() << "FRegion Out: ";
FRegion.dump(llvm::errs());
llvm::errs() << "\n";
#endif
FRegion.reset(i, FBound);
}
}
