switches_zerodim.hpp

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//This file is part of Bertini 2.
//
//bertini2/blackbox/switches_zerodim.hpp is free software: you can redistribute it and/or modify
//it under the terms of the GNU General Public License as published by
//the Free Software Foundation, either version 3 of the License, or
//(at your option) any later version.
//
//bertini2/blackbox/switches_zerodim.hpp is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//GNU General Public License for more details.
//
//You should have received a copy of the GNU General Public License
//along with bertini2/blackbox/switches_zerodim.hpp.  If not, see <http://www.gnu.org/licenses/>.
//
// Copyright(C) Bertini2 Development Team
//
// See <http://www.gnu.org/licenses/> for a copy of the license,
// as well as COPYING.  Bertini2 is provided with permitted
// additional terms in the b2/licenses/ directory.
//
// silviana amethyst, university of wisconsin-eau claire

 
 
 
#pragma once
 
 
#include "bertini2/system.hpp"
#include "bertini2/nag_algorithms/zero_dim_solve.hpp"
#include "bertini2/endgames.hpp"
 
#include "bertini2/blackbox/config.hpp"
 
 
namespace bertini{
namespace blackbox{
 
 

struct ZeroDimRT
{
    // INTERIM default = TotalDegreeBinomial (see policies.hpp): the linear-product TotalDegreeLinearProduct is the
    // eventual default but currently stalls the Cauchy endgame on harder systems, so the safe
    // default stays roots of unity until that is fixed.
    type::Start start = type::Start::TotalDegreeBinomial;  
    type::Tracker tracker = type::Tracker::Adaptive;       
    type::Endgame endgame = type::Endgame::Cauchy;         
};
 

inline type::Start InferStartType(System const& sys)
{
    // INTERIM: a single affine group infers TotalDegreeBinomial (the safe default).  The eventual choice
    // here is TotalDegreeLinearProduct (general position), gated on the Cauchy-endgame fix; see policies.hpp.
    if (sys.NumVariableGroups() == 1 && sys.NumHomVariableGroups() == 0)
        return type::Start::TotalDegreeBinomial;
    else
        return type::Start::MHom;
}
 
 
// The concrete start-system type appears only at the construction site, via
// start_system::MakeStartFactory<StartType>() (see start_base.hpp); ZeroDim downstream is a
// single type that holds the start system polymorphically.  Add a start system => add a
// case in ZeroDimSpecifyStart, no new ZeroDim instantiation.

template <typename TrackerType, typename EndgameType, typename ... ConstTs>
std::unique_ptr<algorithm::AnyZeroDim> ZeroDimSpecifyComplete(ConstTs const& ...ts)
{
    // the blackbox always clones + builds (ZeroDimSolver); ts... = (target, start_factory).
    return std::make_unique<
            algorithm::ZeroDimSolver<TrackerType, EndgameType, System>
            >(ts...);
}

template <typename TrackerType, typename ... ConstTs>
std::unique_ptr<algorithm::AnyZeroDim> ZeroDimSpecifyEndgame(ZeroDimRT const& rt, ConstTs const& ...ts)
{
    switch (rt.endgame)
    {
        case type::Endgame::PowerSeries:
            // honor the requested endgame!  until 2026-06-12 this hardcoded Cauchy.
            return ZeroDimSpecifyComplete<TrackerType,
                    typename endgame::EndgameSelector<TrackerType>::PSEG>(ts...);
 
        case type::Endgame::Cauchy:
            return ZeroDimSpecifyComplete<TrackerType,
                    typename endgame::EndgameSelector<TrackerType>::Cauchy>(ts...);
    }
    throw std::runtime_error("unrecognized endgame type in ZeroDimSpecifyEndgame");
}

template <typename ... ConstTs>
std::unique_ptr<algorithm::AnyZeroDim> ZeroDimSpecifyTracker(ZeroDimRT const& rt, ConstTs const& ...ts)
{
    switch (rt.tracker)
    {
        case type::Tracker::FixedDouble:
            return ZeroDimSpecifyEndgame<tracking::DoublePrecisionTracker>(rt, ts...);
        case type::Tracker::FixedMultiple:
            return ZeroDimSpecifyEndgame<tracking::MultiplePrecisionTracker>(rt, ts...);
        case type::Tracker::Adaptive:
            return ZeroDimSpecifyEndgame<tracking::AMPTracker>(rt, ts...);
    }
    throw std::runtime_error("unrecognized tracker type in ZeroDimSpecifyTracker");
}

template <typename ... ConstTs>
std::unique_ptr<algorithm::AnyZeroDim> ZeroDimSpecifyStart(ZeroDimRT const& rt, ConstTs const& ...ts)
{
    // append the start-system factory to the argument pack; ZeroDimSolver consumes (target, factory).
    switch (rt.start)
    {
        case type::Start::TotalDegreeLinearProduct:
            return ZeroDimSpecifyTracker(rt, ts..., start_system::MakeStartFactory<start_system::TotalDegreeLinearProduct>());
        case type::Start::TotalDegreeBinomial:
            return ZeroDimSpecifyTracker(rt, ts..., start_system::MakeStartFactory<start_system::TotalDegreeBinomial>());
        case type::Start::MHom:
            return ZeroDimSpecifyTracker(rt, ts..., start_system::MakeStartFactory<start_system::MHomogeneous>());
        case type::Start::User:
            throw std::runtime_error("trying to use generic zero dim with user homotopy.  use the specific UserBlaBla instead");
    }
    throw std::runtime_error("unrecognized start system type in ZeroDimSpecifyStart");
}

template <typename ... ConstTs>
std::unique_ptr<algorithm::AnyZeroDim> MakeZeroDim(ZeroDimRT const& rt, ConstTs const& ...ts)
{
    return ZeroDimSpecifyStart(rt, ts...);
}
 
 
} //ns blackbox
} //ns bertini