Add Iterative Refinement

Add a class IterativeRefiner which implements iterative refinement
for SPD linear systems.

Change-Id: I705d4e96cb7de9226ee35e2a9c11d98ffc0ee239
This commit is contained in:
Sameer Agarwal
2018-04-05 11:48:26 -07:00
parent 9814a91fcf
commit 86814ab193
6 changed files with 419 additions and 0 deletions
+1
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@@ -112,6 +112,7 @@ CERES_TESTS = [
"inner_product_computer",
"invert_psd_matrix",
"is_close",
"iterative_refiner",
"iterative_schur_complement_solver",
"jet",
"levenberg_marquardt_strategy",
+1
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@@ -74,6 +74,7 @@ CERES_SRCS = ["internal/ceres/" + filename for filename in [
"is_close.cc",
"implicit_schur_complement.cc",
"inner_product_computer.cc",
"iterative_refiner.cc",
"iterative_schur_complement_solver.cc",
"lapack.cc",
"levenberg_marquardt_strategy.cc",
+2
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@@ -75,6 +75,7 @@ set(CERES_INTERNAL_SRC
implicit_schur_complement.cc
inner_product_computer.cc
is_close.cc
iterative_refiner.cc
iterative_schur_complement_solver.cc
levenberg_marquardt_strategy.cc
lapack.cc
@@ -338,6 +339,7 @@ if (BUILD_TESTING AND GFLAGS)
ceres_test(inner_product_computer)
ceres_test(invert_psd_matrix)
ceres_test(is_close)
ceres_test(iterative_refiner)
ceres_test(iterative_schur_complement_solver)
ceres_test(jet)
ceres_test(levenberg_marquardt_strategy)
+112
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@@ -0,0 +1,112 @@
// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2018 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: sameeragarwal@google.com (Sameer Agarwal)
#include <string>
#include "ceres/iterative_refiner.h"
#include "Eigen/Core"
#include "ceres/sparse_cholesky.h"
#include "ceres/sparse_matrix.h"
namespace ceres {
namespace internal {
IterativeRefiner::IterativeRefiner(const int num_cols,
const int max_num_iterations)
: num_cols_(num_cols),
max_num_iterations_(max_num_iterations),
residual_(num_cols),
correction_(num_cols),
lhs_x_solution_(num_cols) {}
IterativeRefiner::Summary IterativeRefiner::Refine(
const SparseMatrix& lhs,
const double* rhs_ptr,
SparseCholesky* sparse_cholesky,
double* solution_ptr) {
Summary summary;
ConstVectorRef rhs(rhs_ptr, num_cols_);
VectorRef solution(solution_ptr, num_cols_);
summary.lhs_max_norm = ConstVectorRef(lhs.values(), lhs.num_nonzeros())
.lpNorm<Eigen::Infinity>();
summary.rhs_max_norm = rhs.lpNorm<Eigen::Infinity>();
summary.solution_max_norm = solution.lpNorm<Eigen::Infinity>();
// residual = rhs - lhs * solution
lhs_x_solution_.setZero();
lhs.RightMultiply(solution_ptr, lhs_x_solution_.data());
residual_ = rhs - lhs_x_solution_;
summary.residual_max_norm = residual_.lpNorm<Eigen::Infinity>();
for (summary.num_iterations = 0;
summary.num_iterations < max_num_iterations_;
++summary.num_iterations) {
// Check the current solution for convergence.
const double kTolerance = 5e-15; // From Hogg & Scott.
// residual_tolerance = (|A| |x| + |b|) * kTolerance;
const double residual_tolerance =
(summary.lhs_max_norm * summary.solution_max_norm +
summary.rhs_max_norm) *
kTolerance;
VLOG(3) << "Refinement:"
<< " iter: " << summary.num_iterations
<< " |A|: " << summary.lhs_max_norm
<< " |b|: " << summary.rhs_max_norm
<< " |x|: " << summary.solution_max_norm
<< " |b - Ax|: " << summary.residual_max_norm
<< " tol: " << residual_tolerance;
// |b - Ax| < (|A| |x| + |b|) * kTolerance;
if (summary.residual_max_norm < residual_tolerance) {
summary.converged = true;
break;
}
// Solve for lhs * correction = residual
correction_.setZero();
std::string ignored_message;
sparse_cholesky->Solve(
residual_.data(), correction_.data(), &ignored_message);
solution += correction_;
summary.solution_max_norm = solution.lpNorm<Eigen::Infinity>();
// residual = rhs - lhs * solution
lhs_x_solution_.setZero();
lhs.RightMultiply(solution_ptr, lhs_x_solution_.data());
residual_ = rhs - lhs_x_solution_;
summary.residual_max_norm = residual_.lpNorm<Eigen::Infinity>();
}
return summary;
};
} // namespace internal
} // namespace ceres
+111
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@@ -0,0 +1,111 @@
// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2018 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: sameeragarwal@google.com (Sameer Agarwal)
#ifndef CERES_INTERNAL_ITERATIVE_REFINER_H_
#define CERES_INTERNAL_ITERATIVE_REFINER_H_
// This include must come before any #ifndef check on Ceres compile options.
#include "ceres/internal/port.h"
#include "ceres/internal/eigen.h"
namespace ceres {
namespace internal {
class SparseMatrix;
class SparseCholesky;
// Iterative refinement
// (https://en.wikipedia.org/wiki/Iterative_refinement) is the process
// of improving the solution to a linear system, by using the
// following iteration.
//
// r_i = b - Ax_i
// Ad_i = r_i
// x_{i+1} = x_i + d_i
//
// IterativeRefiner implements this process for Symmetric Positive
// Definite linear systems.
//
// The above iterative loop is run until max_num_iterations is reached
// or the following convergence criterion is satisfied:
//
// |b - Ax|
// ------------- < 5e-15
// |A| |x| + |b|
//
// All norms in the above expression are max-norms. The above
// expression is what is recommended and used by Hogg & Scott in "A
// fast and robust mixed-precision solver for the solution of sparse
// symmetric linear systems".
//
// For example usage, please see sparse_normal_cholesky_solver.cc
class IterativeRefiner {
public:
struct Summary {
bool converged = false;
int num_iterations = -1;
double lhs_max_norm = -1;
double rhs_max_norm = -1;
double solution_max_norm = -1;
double residual_max_norm = -1;
};
// num_cols is the number of rows & columns in the linear system
// being solved.
//
// max_num_iterations is the maximum number of refinement iterations
// to perform.
IterativeRefiner(int num_cols, int max_num_iterations);
// Given an initial estimate of the solution of lhs * x = rhs, use
// iterative refinement to improve it.
//
// sparse_cholesky is assumed to contain an already computed
// factorization (or approximation thereof) of lhs.
//
// solution is expected to contain a approximation to the solution
// to lhs * x = rhs. It can be zero.
Summary Refine(const SparseMatrix& lhs,
const double* rhs,
SparseCholesky* sparse_cholesky,
double* solution);
private:
int num_cols_;
int max_num_iterations_;
Vector residual_;
Vector correction_;
Vector lhs_x_solution_;
};
} // namespace internal
} // namespace ceres
#endif // CERES_INTERNAL_ITERATIVE_REFINER_H_
+192
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@@ -0,0 +1,192 @@
// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2018 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: sameeragarwal@google.com (Sameer Agarwal)
#include "Eigen/Dense"
#include "ceres/iterative_refiner.h"
#include "ceres/internal/eigen.h"
#include "ceres/sparse_cholesky.h"
#include "ceres/sparse_matrix.h"
#include "glog/logging.h"
#include "gtest/gtest.h"
namespace ceres {
namespace internal {
// Macros to help us define virtual methods which we do not expect to
// use/call in this test.
#define DO_NOT_CALL \
{ LOG(FATAL) << "DO NOT CALL"; }
#define DO_NOT_CALL_WITH_RETURN(x) \
{ \
LOG(FATAL) << "DO NOT CALL"; \
return x; \
}
// A fake SparseMatrix, which uses an Eigen matrix to do the real work.
class FakeSparseMatrix : public SparseMatrix {
public:
FakeSparseMatrix(const Matrix& m) : m_(m) {}
virtual ~FakeSparseMatrix() {}
// y += Ax
virtual void RightMultiply(const double* x, double* y) const {
VectorRef(y, m_.cols()) += m_ * ConstVectorRef(x, m_.cols());
}
// y += A'x
virtual void LeftMultiply(const double* x, double* y) const {
// We will assume that this is a symmetric matrix.
RightMultiply(x, y);
}
virtual double* mutable_values() { return m_.data(); }
virtual const double* values() const { return m_.data(); }
virtual int num_rows() const { return m_.cols(); }
virtual int num_cols() const { return m_.cols(); }
virtual int num_nonzeros() const {return m_.cols() * m_.cols(); }
// The following methods are not needed for tests in this file.
virtual void SquaredColumnNorm(double* x) const DO_NOT_CALL;
virtual void ScaleColumns(const double* scale) DO_NOT_CALL;
virtual void SetZero() DO_NOT_CALL;
virtual void ToDenseMatrix(Matrix* dense_matrix) const DO_NOT_CALL;
virtual void ToTextFile(FILE* file) const DO_NOT_CALL;
private:
Matrix m_;
};
// A fake SparseCholesky which uses Eigen's Cholesky factorization to
// do the real work. The template parameter allows us to work in
// doubles or floats, even though the source matrix is double.
template <typename Scalar>
class FakeSparseCholesky : public SparseCholesky {
public:
FakeSparseCholesky(const Matrix& lhs) { lhs_ = lhs.cast<Scalar>(); }
virtual ~FakeSparseCholesky() {}
virtual LinearSolverTerminationType Solve(const double* rhs_ptr,
double* solution_ptr,
std::string* message) {
const int num_cols = lhs_.cols();
VectorRef solution(solution_ptr, num_cols);
ConstVectorRef rhs(rhs_ptr, num_cols);
solution = lhs_.llt().solve(rhs.cast<Scalar>()).template cast<double>();
return LINEAR_SOLVER_SUCCESS;
}
// The following methods are not needed for tests in this file.
virtual CompressedRowSparseMatrix::StorageType StorageType() const
DO_NOT_CALL_WITH_RETURN(CompressedRowSparseMatrix::UPPER_TRIANGULAR);
virtual LinearSolverTerminationType Factorize(CompressedRowSparseMatrix* lhs,
std::string* message)
DO_NOT_CALL_WITH_RETURN(LINEAR_SOLVER_FAILURE);
virtual LinearSolverTerminationType FactorAndSolve(
CompressedRowSparseMatrix* lhs,
const double* rhs,
double* solution,
std::string* message) DO_NOT_CALL_WITH_RETURN(LINEAR_SOLVER_FAILURE);
private:
Eigen::Matrix<Scalar, Eigen::Dynamic, Eigen::Dynamic> lhs_;
};
#undef DO_NOT_CALL
#undef DO_NOT_CALL_WITH_RETURN
class IterativeRefinerTest : public ::testing::Test {
public:
void SetUp() {
num_cols_ = 5;
max_num_iterations_ = 30;
Matrix m(num_cols_, num_cols_);
m.setRandom();
lhs_ = m * m.transpose();
solution_.resize(num_cols_);
solution_.setRandom();
rhs_ = lhs_ * solution_;
};
protected:
int num_cols_;
int max_num_iterations_;
Matrix lhs_;
Vector rhs_;
Vector solution_;
};
TEST_F(IterativeRefinerTest,
ExactSolutionWithExactFactorizationReturnsInZeroIterations) {
FakeSparseMatrix lhs(lhs_);
FakeSparseCholesky<double> sparse_cholesky(lhs_);
IterativeRefiner refiner(num_cols_, max_num_iterations_);
Vector refined_solution = solution_;
auto summary = refiner.Refine(
lhs, rhs_.data(), &sparse_cholesky, refined_solution.data());
EXPECT_EQ(summary.num_iterations, 0);
EXPECT_TRUE(summary.converged);
EXPECT_NEAR(
(refined_solution - solution_).norm() / solution_.norm(), 0.0, 5e-15);
}
TEST_F(IterativeRefinerTest,
RandomSolutionWithExactFactorizationReturnsInOneIteration) {
FakeSparseMatrix lhs(lhs_);
FakeSparseCholesky<double> sparse_cholesky(lhs_);
IterativeRefiner refiner(num_cols_, max_num_iterations_);
Vector refined_solution(num_cols_);
refined_solution.setRandom();
auto summary = refiner.Refine(
lhs, rhs_.data(), &sparse_cholesky, refined_solution.data());
EXPECT_EQ(summary.num_iterations, 1);
EXPECT_TRUE(summary.converged);
EXPECT_NEAR(
(refined_solution - solution_).norm() / solution_.norm(), 0.0, 5e-15);
}
TEST_F(IterativeRefinerTest,
RandomSolutionWithApproximationFactorizationConverges) {
FakeSparseMatrix lhs(lhs_);
// Use a single precision Cholesky factorization of the double
// precision matrix. This will give us an approximate factorization.
FakeSparseCholesky<float> sparse_cholesky(lhs_);
IterativeRefiner refiner(num_cols_, max_num_iterations_);
Vector refined_solution(num_cols_);
refined_solution.setRandom();
auto summary = refiner.Refine(
lhs, rhs_.data(), &sparse_cholesky, refined_solution.data());
EXPECT_TRUE(summary.converged);
EXPECT_NEAR(
(refined_solution - solution_).norm() / solution_.norm(), 0.0, 5e-15);
}
} // namespace internal
} // namespace ceres