FunctionMinimum VariableMetricBuilder::minimum(const MnFcn& fcn,
const GradientCalculator& gc, const MinimumSeed& seed,
std::vector<MinimumState>& result, unsigned int maxfcn, double edmval) const {
const MnMachinePrecision& prec = seed.precision();
// result.push_back(MinimumState(seed.parameters(), seed.error(), seed.gradient(), edm, fcn.numOfCalls()));
const MinimumState & initialState = result.back();
double edm = initialState.edm();
#ifdef DEBUG
std::cout << "\n\nDEBUG Variable Metric Builder \nInitial State: "
<< " Parameter " << initialState.vec()
<< " Gradient " << initialState.gradient().vec()
<< " Inv Hessian " << initialState.error().invHessian()
<< " edm = " << initialState.edm() << std::endl;
#endif
// iterate until edm is small enough or max # of iterations reached
edm *= (1. + 3.*initialState.error().dcovar());
MnLineSearch lsearch;
MnAlgebraicVector step(initialState.gradient().vec().size());
// keep also prevStep
MnAlgebraicVector prevStep(initialState.gradient().vec().size());
do {
// const MinimumState& s0 = result.back();
MinimumState s0 = result.back();
step = -1.*s0.error().invHessian()*s0.gradient().vec();
#ifdef DEBUG
std::cout << "\n\n---> Iteration - " << result.size()
<< "\nFval = " << s0.fval() << " numOfCall = " << fcn.numOfCalls()
<< "\nInternal Parameter values " << s0.vec()
<< " Newton step " << step << std::endl;
#endif
double gdel = inner_product(step, s0.gradient().grad());
if(gdel > 0.) {
std::cout<<"VariableMetricBuilder: matrix not pos.def."<<std::endl;
std::cout<<"gdel > 0: "<<gdel<<std::endl;
MnPosDef psdf;
s0 = psdf(s0, prec);
step = -1.*s0.error().invHessian()*s0.gradient().vec();
// #ifdef DEBUG
// std::cout << "After MnPosdef - error " << s0.error().invHessian() << " gradient " << s0.gradient().vec() << " step " << step << std::endl;
// #endif
gdel = inner_product(step, s0.gradient().grad());
std::cout<<"gdel: "<<gdel<<std::endl;
if(gdel > 0.) {
result.push_back(s0);
return FunctionMinimum(seed, result, fcn.up());
}
}
MnParabolaPoint pp = lsearch(fcn, s0.parameters(), step, gdel, prec);
if(fabs(pp.y() - s0.fval()) < fabs(s0.fval())*prec.eps() ) {
if(VariableMetricBuilder::print_level>=1){
std::cout<<"VariableMetricBuilder: warning: no improvement in line search " << std::endl;
}
// no improvement exit (is it really needed LM ? in vers. 1.22 tried alternative )
break;
}
#ifdef DEBUG
std::cout << "Result after line search : \nx = " << pp.x()
<< "\nOld Fval = " << s0.fval()
<< "\nNew Fval = " << pp.y()
<< "\nNFcalls = " << fcn.numOfCalls() << std::endl;
#endif
MinimumParameters p(s0.vec() + pp.x()*step, pp.y());
FunctionGradient g = gc(p, s0.gradient());
edm = estimator().estimate(g, s0.error());
if(edm < 0.) {
std::cout<<"VariableMetricBuilder: matrix not pos.def."<<std::endl;
std::cout<<"edm < 0"<<std::endl;
MnPosDef psdf;
s0 = psdf(s0, prec);
edm = estimator().estimate(g, s0.error());
if(edm < 0.) {
result.push_back(s0);
return FunctionMinimum(seed, result, fcn.up());
}
}
MinimumError e = errorUpdator().update(s0, p, g);
#ifdef DEBUG
std::cout << "Updated new point: \n "
<< " Parameter " << p.vec()
<< " Gradient " << g.vec()
<< " InvHessian " << e.matrix()
<< " Hessian " << e.hessian()
<< " edm = " << edm << std::endl << std::endl;
#endif
result.push_back(MinimumState(p, e, g, edm, fcn.numOfCalls()));
// correct edm
edm *= (1. + 3.*e.dcovar());
#ifdef DEBUG
std::cout << "edm corrected = " << edm << std::endl;
#endif
FunctionMinimum tmp(seed, result, fcn.up());
if(VariableMetricBuilder::print_level >= 2){
printProgress(fcn);
tmp.print(true);
}
} while(edm > edmval && fcn.numOfCalls() < maxfcn);
if(fcn.numOfCalls() >= maxfcn) {
std::cout<<"VariableMetricBuilder: call limit exceeded."<<std::endl;
return FunctionMinimum(seed, result, fcn.up(), FunctionMinimum::MnReachedCallLimit());
}
if(edm > edmval) {
if(edm < fabs(prec.eps2()*result.back().fval())) {
std::cout<<"VariableMetricBuilder: machine accuracy limits further improvement."<<std::endl;
return FunctionMinimum(seed, result, fcn.up());
} else if(edm < 10.*edmval) {
return FunctionMinimum(seed, result, fcn.up());
} else {
std::cout<<"VariableMetricBuilder: finishes without convergence."<<std::endl;
std::cout<<"VariableMetricBuilder: edm= "<<edm<<" requested: "<<edmval<<std::endl;
return FunctionMinimum(seed, result, fcn.up(), FunctionMinimum::MnAboveMaxEdm());
}
}
//std::cout<<"result.back().error().dcovar()= "<<result.back().error().dcovar()<<std::endl;
#ifdef DEBUG
std::cout << "Exiting succesfully Variable Metric Builder \n"
<< "NFCalls = " << fcn.numOfCalls()
<< "\nFval = " << result.back().fval()
<< "\nedm = " << edm << " requested = " << edmval << std::endl;
#endif
return FunctionMinimum(seed, result, fcn.up());
}
