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-rw-r--r--absl/random/internal/generate_real.h4
-rw-r--r--absl/random/uniform_real_distribution.h2
-rw-r--r--absl/random/uniform_real_distribution_test.cc121
3 files changed, 82 insertions, 45 deletions
diff --git a/absl/random/internal/generate_real.h b/absl/random/internal/generate_real.h
index d5fbb44c..b569450c 100644
--- a/absl/random/internal/generate_real.h
+++ b/absl/random/internal/generate_real.h
@@ -50,10 +50,10 @@ struct GenerateSignedTag {};
// inputs, otherwise it never returns 0.
//
// When a value in U(0,1) is required, use:
-// Uniform64ToReal<double, PositiveValueT, true>;
+// GenerateRealFromBits<double, PositiveValueT, true>;
//
// When a value in U(-1,1) is required, use:
-// Uniform64ToReal<double, SignedValueT, false>;
+// GenerateRealFromBits<double, SignedValueT, false>;
//
// This generates more distinct values than the mathematical equivalent
// `U(0, 1) * 2.0 - 1.0`.
diff --git a/absl/random/uniform_real_distribution.h b/absl/random/uniform_real_distribution.h
index 5ba17b23..19683341 100644
--- a/absl/random/uniform_real_distribution.h
+++ b/absl/random/uniform_real_distribution.h
@@ -73,12 +73,12 @@ class uniform_real_distribution {
: lo_(lo), hi_(hi), range_(hi - lo) {
// [rand.dist.uni.real] preconditions 2 & 3
assert(lo <= hi);
+
// NOTE: For integral types, we can promote the range to an unsigned type,
// which gives full width of the range. However for real (fp) types, this
// is not possible, so value generation cannot use the full range of the
// real type.
assert(range_ <= (std::numeric_limits<result_type>::max)());
- assert(std::isfinite(range_));
}
result_type a() const { return lo_; }
diff --git a/absl/random/uniform_real_distribution_test.cc b/absl/random/uniform_real_distribution_test.cc
index 035bd284..07f199d3 100644
--- a/absl/random/uniform_real_distribution_test.cc
+++ b/absl/random/uniform_real_distribution_test.cc
@@ -78,62 +78,74 @@ TYPED_TEST(UniformRealDistributionTest, ParamSerializeTest) {
GTEST_SKIP()
<< "Skipping the test because we detected x87 floating-point semantics";
#endif
+ using DistributionType = absl::uniform_real_distribution<TypeParam>;
+ using real_type = TypeParam;
+ using param_type = typename DistributionType::param_type;
- using param_type =
- typename absl::uniform_real_distribution<TypeParam>::param_type;
+ constexpr const real_type kMax = std::numeric_limits<real_type>::max();
+ constexpr const real_type kMin = std::numeric_limits<real_type>::min();
+ constexpr const real_type kEpsilon =
+ std::numeric_limits<real_type>::epsilon();
+ constexpr const real_type kLowest =
+ std::numeric_limits<real_type>::lowest(); // -max
- constexpr const TypeParam a{1152921504606846976};
+ const real_type kDenormMax = std::nextafter(kMin, real_type{0});
+ const real_type kOneMinusE =
+ std::nextafter(real_type{1}, real_type{0}); // 1 - epsilon
+
+ constexpr const real_type kTwo60{1152921504606846976}; // 2^60
constexpr int kCount = 1000;
absl::InsecureBitGen gen;
for (const auto& param : {
param_type(),
- param_type(TypeParam(2.0), TypeParam(2.0)), // Same
- param_type(TypeParam(-0.1), TypeParam(0.1)),
- param_type(TypeParam(0.05), TypeParam(0.12)),
- param_type(TypeParam(-0.05), TypeParam(0.13)),
- param_type(TypeParam(-0.05), TypeParam(-0.02)),
+ param_type(real_type{0}, real_type{1}),
+ param_type(real_type(-0.1), real_type(0.1)),
+ param_type(real_type(0.05), real_type(0.12)),
+ param_type(real_type(-0.05), real_type(0.13)),
+ param_type(real_type(-0.05), real_type(-0.02)),
+ // range = 0
+ param_type(real_type(2.0), real_type(2.0)), // Same
// double range = 0
// 2^60 , 2^60 + 2^6
- param_type(a, TypeParam(1152921504606847040)),
+ param_type(kTwo60, real_type(1152921504606847040)),
// 2^60 , 2^60 + 2^7
- param_type(a, TypeParam(1152921504606847104)),
+ param_type(kTwo60, real_type(1152921504606847104)),
// double range = 2^8
// 2^60 , 2^60 + 2^8
- param_type(a, TypeParam(1152921504606847232)),
+ param_type(kTwo60, real_type(1152921504606847232)),
// float range = 0
// 2^60 , 2^60 + 2^36
- param_type(a, TypeParam(1152921573326323712)),
+ param_type(kTwo60, real_type(1152921573326323712)),
// 2^60 , 2^60 + 2^37
- param_type(a, TypeParam(1152921642045800448)),
+ param_type(kTwo60, real_type(1152921642045800448)),
// float range = 2^38
// 2^60 , 2^60 + 2^38
- param_type(a, TypeParam(1152921779484753920)),
+ param_type(kTwo60, real_type(1152921779484753920)),
// Limits
- param_type(0, std::numeric_limits<TypeParam>::max()),
- param_type(std::numeric_limits<TypeParam>::lowest(), 0),
- param_type(0, std::numeric_limits<TypeParam>::epsilon()),
- param_type(-std::numeric_limits<TypeParam>::epsilon(),
- std::numeric_limits<TypeParam>::epsilon()),
- param_type(std::numeric_limits<TypeParam>::epsilon(),
- 2 * std::numeric_limits<TypeParam>::epsilon()),
+ param_type(0, kMax),
+ param_type(kLowest, 0),
+ param_type(0, kMin),
+ param_type(0, kEpsilon),
+ param_type(-kEpsilon, kEpsilon),
+ param_type(0, kOneMinusE),
+ param_type(0, kDenormMax),
}) {
// Validate parameters.
const auto a = param.a();
const auto b = param.b();
- absl::uniform_real_distribution<TypeParam> before(a, b);
+ DistributionType before(a, b);
EXPECT_EQ(before.a(), param.a());
EXPECT_EQ(before.b(), param.b());
{
- absl::uniform_real_distribution<TypeParam> via_param(param);
+ DistributionType via_param(param);
EXPECT_EQ(via_param, before);
}
std::stringstream ss;
ss << before;
- absl::uniform_real_distribution<TypeParam> after(TypeParam(1.0),
- TypeParam(3.1));
+ DistributionType after(real_type(1.0), real_type(3.1));
EXPECT_NE(before.a(), after.a());
EXPECT_NE(before.b(), after.b());
@@ -168,7 +180,7 @@ TYPED_TEST(UniformRealDistributionTest, ParamSerializeTest) {
}
}
- if (!std::is_same<TypeParam, long double>::value) {
+ if (!std::is_same<real_type, long double>::value) {
// static_cast<double>(long double) can overflow.
std::string msg = absl::StrCat("Range: ", static_cast<double>(sample_min),
", ", static_cast<double>(sample_max));
@@ -182,33 +194,52 @@ TYPED_TEST(UniformRealDistributionTest, ParamSerializeTest) {
#pragma warning(disable:4756) // Constant arithmetic overflow.
#endif
TYPED_TEST(UniformRealDistributionTest, ViolatesPreconditionsDeathTest) {
+ using DistributionType = absl::uniform_real_distribution<TypeParam>;
+ using real_type = TypeParam;
+
#if GTEST_HAS_DEATH_TEST
// Hi < Lo
- EXPECT_DEBUG_DEATH(
- { absl::uniform_real_distribution<TypeParam> dist(10.0, 1.0); }, "");
+ EXPECT_DEBUG_DEATH({ DistributionType dist(10.0, 1.0); }, "");
// Hi - Lo > numeric_limits<>::max()
EXPECT_DEBUG_DEATH(
{
- absl::uniform_real_distribution<TypeParam> dist(
- std::numeric_limits<TypeParam>::lowest(),
- std::numeric_limits<TypeParam>::max());
+ DistributionType dist(std::numeric_limits<real_type>::lowest(),
+ std::numeric_limits<real_type>::max());
+ },
+ "");
+
+ // kEpsilon guarantees that max + kEpsilon = inf.
+ const auto kEpsilon = std::nexttoward(
+ (std::numeric_limits<real_type>::max() -
+ std::nexttoward(std::numeric_limits<real_type>::max(), 0.0)) /
+ 2,
+ std::numeric_limits<real_type>::max());
+ EXPECT_DEBUG_DEATH(
+ {
+ DistributionType dist(-kEpsilon, std::numeric_limits<real_type>::max());
},
"");
+ EXPECT_DEBUG_DEATH(
+ {
+ DistributionType dist(std::numeric_limits<real_type>::lowest(),
+ kEpsilon);
+ },
+ "");
+
#endif // GTEST_HAS_DEATH_TEST
#if defined(NDEBUG)
// opt-mode, for invalid parameters, will generate a garbage value,
// but should not enter an infinite loop.
absl::InsecureBitGen gen;
{
- absl::uniform_real_distribution<TypeParam> dist(10.0, 1.0);
+ DistributionType dist(10.0, 1.0);
auto x = dist(gen);
EXPECT_FALSE(std::isnan(x)) << x;
}
{
- absl::uniform_real_distribution<TypeParam> dist(
- std::numeric_limits<TypeParam>::lowest(),
- std::numeric_limits<TypeParam>::max());
+ DistributionType dist(std::numeric_limits<real_type>::lowest(),
+ std::numeric_limits<real_type>::max());
auto x = dist(gen);
// Infinite result.
EXPECT_FALSE(std::isfinite(x)) << x;
@@ -220,6 +251,8 @@ TYPED_TEST(UniformRealDistributionTest, ViolatesPreconditionsDeathTest) {
#endif
TYPED_TEST(UniformRealDistributionTest, TestMoments) {
+ using DistributionType = absl::uniform_real_distribution<TypeParam>;
+
constexpr int kSize = 1000000;
std::vector<double> values(kSize);
@@ -228,7 +261,7 @@ TYPED_TEST(UniformRealDistributionTest, TestMoments) {
// implementation.
absl::random_internal::pcg64_2018_engine rng{0x2B7E151628AED2A6};
- absl::uniform_real_distribution<TypeParam> dist;
+ DistributionType dist;
for (int i = 0; i < kSize; i++) {
values[i] = dist(rng);
}
@@ -242,9 +275,10 @@ TYPED_TEST(UniformRealDistributionTest, TestMoments) {
}
TYPED_TEST(UniformRealDistributionTest, ChiSquaredTest50) {
+ using DistributionType = absl::uniform_real_distribution<TypeParam>;
+ using param_type = typename DistributionType::param_type;
+
using absl::random_internal::kChiSquared;
- using param_type =
- typename absl::uniform_real_distribution<TypeParam>::param_type;
constexpr size_t kTrials = 100000;
constexpr int kBuckets = 50;
@@ -269,7 +303,7 @@ TYPED_TEST(UniformRealDistributionTest, ChiSquaredTest50) {
const double factor = kBuckets / (max_val - min_val);
std::vector<int32_t> counts(kBuckets, 0);
- absl::uniform_real_distribution<TypeParam> dist(param);
+ DistributionType dist(param);
for (size_t i = 0; i < kTrials; i++) {
auto x = dist(rng);
auto bucket = static_cast<size_t>((x - min_val) * factor);
@@ -297,8 +331,11 @@ TYPED_TEST(UniformRealDistributionTest, ChiSquaredTest50) {
}
TYPED_TEST(UniformRealDistributionTest, StabilityTest) {
+ using DistributionType = absl::uniform_real_distribution<TypeParam>;
+ using real_type = TypeParam;
+
// absl::uniform_real_distribution stability relies only on
- // random_internal::RandU64ToDouble and random_internal::RandU64ToFloat.
+ // random_internal::GenerateRealFromBits.
absl::random_internal::sequence_urbg urbg(
{0x0003eb76f6f7f755ull, 0xFFCEA50FDB2F953Bull, 0xC332DDEFBE6C5AA5ull,
0x6558218568AB9702ull, 0x2AEF7DAD5B6E2F84ull, 0x1521B62829076170ull,
@@ -307,9 +344,9 @@ TYPED_TEST(UniformRealDistributionTest, StabilityTest) {
std::vector<int> output(12);
- absl::uniform_real_distribution<TypeParam> dist;
+ DistributionType dist;
std::generate(std::begin(output), std::end(output), [&] {
- return static_cast<int>(TypeParam(1000000) * dist(urbg));
+ return static_cast<int>(real_type(1000000) * dist(urbg));
});
EXPECT_THAT(
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-07 19:56:17 +0000