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Fix line search to avoid non-finite gradients #3309

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Fix line search to avoid non-finite gradients #3309

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801093b
Fix line search to avoid non-finite gradients
cpfiffer Aug 5, 2024
7066ec4
Add test for handling non-finite gradients in WolfeLineSearch
cpfiffer Aug 5, 2024
407b737
add nan and inf test cases to line search
cpfiffer Aug 5, 2024
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2 changes: 1 addition & 1 deletion src/stan/optimization/bfgs_linesearch.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -253,7 +253,7 @@ int WolfeLineSearch(FunctorType &func, Scalar &alpha, XType &x1,

x1.noalias() = x0 + alpha1 * p;
ret = func(x1, func_val, gradx1);
if (ret != 0) {
if (ret != 0 || !std::isfinite(func_val) || !gradx1.allFinite()) {
if (lsRestarts >= maxLSRestarts) {
retCode = 1;
break;
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123 changes: 123 additions & 0 deletions src/test/unit/optimization/bfgs_linesearch_test.cpp
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Expand Up @@ -192,3 +192,126 @@ TEST(OptimizationBfgsLinesearch, wolfeLineSearch) {
EXPECT_LE(f1, f0 + c1 * alpha * p.dot(gradx0));
EXPECT_LE(std::fabs(p.dot(gradx1)), c2 * std::fabs(p.dot(gradx0)));
}

class linesearch_testfunc_nonfinite {
public:
double operator()(const Eigen::Matrix<double, Eigen::Dynamic, 1> &x) {
return x.dot(x) - 1.0;
}
int operator()(const Eigen::Matrix<double, Eigen::Dynamic, 1> &x, double &f,
Eigen::Matrix<double, Eigen::Dynamic, 1> &g) {
f = x.dot(x) - 1.0;
g = 2.0 * x;
if (!g.allFinite()) {
return 1;
}
return 0;
}
};

TEST(OptimizationBfgsLinesearch, wolfeLineSearch_nonfinite_gradient) {
using stan::optimization::WolfeLineSearch;

static const double c1 = 1e-4;
static const double c2 = 0.9;
static const double minAlpha = 1e-16;
static const double maxLSIts = 20;
static const double maxLSRestarts = 10;

linesearch_testfunc_nonfinite func1;
Eigen::Matrix<double, -1, 1> x0, x1;
double f0, f1;
Eigen::Matrix<double, -1, 1> p, gradx0, gradx1;
double alpha;
int ret;

x0.setOnes(5, 1);
func1(x0, f0, gradx0);

p = -gradx0;

alpha = 2.0;
ret = WolfeLineSearch(func1, alpha, x1, f1, gradx1, p, x0, f0, gradx0, c1, c2,
minAlpha, maxLSIts, maxLSRestarts);
EXPECT_EQ(1, ret);
}

class linesearch_testfunc_nan {
public:
double operator()(const Eigen::Matrix<double, Eigen::Dynamic, 1> &x) {
return std::numeric_limits<double>::quiet_NaN();
}
int operator()(const Eigen::Matrix<double, Eigen::Dynamic, 1> &x, double &f,
Eigen::Matrix<double, Eigen::Dynamic, 1> &g) {
f = std::numeric_limits<double>::quiet_NaN();
g = 2.0 * x;
return 1;
}
};

TEST(OptimizationBfgsLinesearch, wolfeLineSearch_nan) {
using stan::optimization::WolfeLineSearch;

static const double c1 = 1e-4;
static const double c2 = 0.9;
static const double minAlpha = 1e-16;
static const double maxLSIts = 20;
static const double maxLSRestarts = 10;

linesearch_testfunc_nan func1;
Eigen::Matrix<double, -1, 1> x0, x1;
double f0, f1;
Eigen::Matrix<double, -1, 1> p, gradx0, gradx1;
double alpha;
int ret;

x0.setOnes(5, 1);
func1(x0, f0, gradx0);

p = -gradx0;

alpha = 2.0;
ret = WolfeLineSearch(func1, alpha, x1, f1, gradx1, p, x0, f0, gradx0, c1, c2,
minAlpha, maxLSIts, maxLSRestarts);
EXPECT_EQ(1, ret);
}

class linesearch_testfunc_inf {
public:
double operator()(const Eigen::Matrix<double, Eigen::Dynamic, 1> &x) {
return std::numeric_limits<double>::infinity();
}
int operator()(const Eigen::Matrix<double, Eigen::Dynamic, 1> &x, double &f,
Eigen::Matrix<double, Eigen::Dynamic, 1> &g) {
f = std::numeric_limits<double>::infinity();
g = 2.0 * x;
return 1;
}
};

TEST(OptimizationBfgsLinesearch, wolfeLineSearch_inf) {
using stan::optimization::WolfeLineSearch;

static const double c1 = 1e-4;
static const double c2 = 0.9;
static const double minAlpha = 1e-16;
static const double maxLSIts = 20;
static const double maxLSRestarts = 10;

linesearch_testfunc_inf func1;
Eigen::Matrix<double, -1, 1> x0, x1;
double f0, f1;
Eigen::Matrix<double, -1, 1> p, gradx0, gradx1;
double alpha;
int ret;

x0.setOnes(5, 1);
func1(x0, f0, gradx0);

p = -gradx0;

alpha = 2.0;
ret = WolfeLineSearch(func1, alpha, x1, f1, gradx1, p, x0, f0, gradx0, c1, c2,
minAlpha, maxLSIts, maxLSRestarts);
EXPECT_EQ(1, ret);
}