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// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla Public License
// v. 2.0. If a copy of the MPL was not distributed with this file, You can
// obtain one at http://mozilla.org/MPL/2.0/.
#ifndef IGL_ACTIVE_SET_H
#define IGL_ACTIVE_SET_H
#include "igl_inline.h"
#include "SolverStatus.h"
#include <Eigen/Core>
#include <Eigen/Sparse>
namespace igl
{
struct active_set_params;
///
/// Minimize convex quadratic energy subject to linear inequality constraints
///
/// min ½ Zᵀ A Z + Zᵀ B + constant
/// Z
/// subject to
/// Aeq Z = Beq
/// Aieq Z <= Bieq
/// lx <= Z <= ux
/// Z(known) = Y
///
/// that Z(known) = Y, optionally also subject to the constraints Aeq*Z = Beq,
/// and further optionally subject to the linear inequality constraints that
/// Aieq*Z <= Bieq and constant inequality constraints lx <= x <= ux
///
/// @param[in] A n by n matrix of quadratic coefficients
/// @param[in] B n by 1 column of linear coefficients
/// @param[in] known list of indices to known rows in Z
/// @param[in] Y list of fixed values corresponding to known rows in Z
/// @param[in] Aeq meq by n list of linear equality constraint coefficients
/// @param[in] Beq meq by 1 list of linear equality constraint constant values
/// @param[in] Aieq mieq by n list of linear inequality constraint coefficients
/// @param[in] Bieq mieq by 1 list of linear inequality constraint constant values
/// @param[in] lx n by 1 list of lower bounds [] implies -Inf
/// @param[in] ux n by 1 list of upper bounds [] implies Inf
/// @param[in] params struct of additional parameters (see below)
/// @param[in,out] Z if not empty, is taken to be an n by 1 list of initial guess values. Set to solution on output.
/// @return true on success, false on error
///
/// \note Benchmark: For a harmonic solve on a mesh with 325K facets, matlab 2.2
/// secs, igl/min_quad_with_fixed.h 7.1 secs
///
/// \pre rows of [Aeq;Aieq] **must** be linearly independent. Should be
/// using QR decomposition otherwise:
/// https://v8doc.sas.com/sashtml/ormp/chap5/sect32.htm
///
/// \warning This solver is fairly experimental. It works reasonably well for
/// bbw problems but doesn't generalize well to other problems. NASOQ and
/// OSQP are better general purpose solvers.
template <
typename AT,
typename DerivedB,
typename Derivedknown,
typename DerivedY,
typename AeqT,
typename DerivedBeq,
typename AieqT,
typename DerivedBieq,
typename Derivedlx,
typename Derivedux,
typename DerivedZ
>
IGL_INLINE igl::SolverStatus active_set(
const Eigen::SparseMatrix<AT>& A,
const Eigen::PlainObjectBase<DerivedB> & B,
const Eigen::PlainObjectBase<Derivedknown> & known,
const Eigen::PlainObjectBase<DerivedY> & Y,
const Eigen::SparseMatrix<AeqT>& Aeq,
const Eigen::PlainObjectBase<DerivedBeq> & Beq,
const Eigen::SparseMatrix<AieqT>& Aieq,
const Eigen::PlainObjectBase<DerivedBieq> & Bieq,
const Eigen::PlainObjectBase<Derivedlx> & lx,
const Eigen::PlainObjectBase<Derivedux> & ux,
const igl::active_set_params & params,
Eigen::PlainObjectBase<DerivedZ> & Z
);
};
#include "EPS.h"
/// Input parameters controling active_set
///
/// \fileinfo
struct igl::active_set_params
{
/// Auu_pd whether Auu is positive definite {false}
bool Auu_pd;
/// max_iter Maximum number of iterations (0 = Infinity, {100})
int max_iter;
/// inactive_threshold Threshold on Lagrange multiplier values to determine
/// whether to keep constraints active {EPS}
double inactive_threshold;
/// constraint_threshold Threshold on whether constraints are violated (0
/// is perfect) {EPS}
double constraint_threshold;
/// solution_diff_threshold Threshold on the squared norm of the difference
/// between two consecutive solutions {EPS}
double solution_diff_threshold;
/// @private
active_set_params():
Auu_pd(false),
max_iter(100),
inactive_threshold(igl::DOUBLE_EPS),
constraint_threshold(igl::DOUBLE_EPS),
solution_diff_threshold(igl::DOUBLE_EPS)
{};
};
#ifndef IGL_STATIC_LIBRARY
# include "active_set.cpp"
#endif
#endif