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Diffstat (limited to 'third_party/abseil_cpp/absl/random/internal/gaussian_distribution_gentables.cc')
-rw-r--r-- | third_party/abseil_cpp/absl/random/internal/gaussian_distribution_gentables.cc | 143 |
1 files changed, 0 insertions, 143 deletions
diff --git a/third_party/abseil_cpp/absl/random/internal/gaussian_distribution_gentables.cc b/third_party/abseil_cpp/absl/random/internal/gaussian_distribution_gentables.cc deleted file mode 100644 index a95333d55f55..000000000000 --- a/third_party/abseil_cpp/absl/random/internal/gaussian_distribution_gentables.cc +++ /dev/null @@ -1,143 +0,0 @@ -// Copyright 2017 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// Generates gaussian_distribution.cc -// -// $ blaze run :gaussian_distribution_gentables > gaussian_distribution.cc -// -#include "absl/random/gaussian_distribution.h" - -#include <cmath> -#include <cstddef> -#include <iostream> -#include <limits> -#include <string> - -#include "absl/base/macros.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace random_internal { -namespace { - -template <typename T, size_t N> -void FormatArrayContents(std::ostream* os, T (&data)[N]) { - if (!std::numeric_limits<T>::is_exact) { - // Note: T is either an integer or a float. - // float requires higher precision to ensure that values are - // reproduced exactly. - // Trivia: C99 has hexadecimal floating point literals, but C++11 does not. - // Using them would remove all concern of precision loss. - os->precision(std::numeric_limits<T>::max_digits10 + 2); - } - *os << " {"; - std::string separator = ""; - for (size_t i = 0; i < N; ++i) { - *os << separator << data[i]; - if ((i + 1) % 3 != 0) { - separator = ", "; - } else { - separator = ",\n "; - } - } - *os << "}"; -} - -} // namespace - -class TableGenerator : public gaussian_distribution_base { - public: - TableGenerator(); - void Print(std::ostream* os); - - using gaussian_distribution_base::kMask; - using gaussian_distribution_base::kR; - using gaussian_distribution_base::kV; - - private: - Tables tables_; -}; - -// Ziggurat gaussian initialization. For an explanation of the algorithm, see -// the Marsaglia paper, "The Ziggurat Method for Generating Random Variables". -// http://www.jstatsoft.org/v05/i08/ -// -// Further details are available in the Doornik paper -// https://www.doornik.com/research/ziggurat.pdf -// -TableGenerator::TableGenerator() { - // The constants here should match the values in gaussian_distribution.h - static constexpr int kC = kMask + 1; - - static_assert((ABSL_ARRAYSIZE(tables_.x) == kC + 1), - "xArray must be length kMask + 2"); - - static_assert((ABSL_ARRAYSIZE(tables_.x) == ABSL_ARRAYSIZE(tables_.f)), - "fx and x arrays must be identical length"); - - auto f = [](double x) { return std::exp(-0.5 * x * x); }; - auto f_inv = [](double x) { return std::sqrt(-2.0 * std::log(x)); }; - - tables_.x[0] = kV / f(kR); - tables_.f[0] = f(tables_.x[0]); - - tables_.x[1] = kR; - tables_.f[1] = f(tables_.x[1]); - - tables_.x[kC] = 0.0; - tables_.f[kC] = f(tables_.x[kC]); // 1.0 - - for (int i = 2; i < kC; i++) { - double v = (kV / tables_.x[i - 1]) + tables_.f[i - 1]; - tables_.x[i] = f_inv(v); - tables_.f[i] = v; - } -} - -void TableGenerator::Print(std::ostream* os) { - *os << "// BEGIN GENERATED CODE; DO NOT EDIT\n" - "// clang-format off\n" - "\n" - "#include \"absl/random/gaussian_distribution.h\"\n" - "\n" - "namespace absl {\n" - "ABSL_NAMESPACE_BEGIN\n" - "namespace random_internal {\n" - "\n" - "const gaussian_distribution_base::Tables\n" - " gaussian_distribution_base::zg_ = {\n"; - FormatArrayContents(os, tables_.x); - *os << ",\n"; - FormatArrayContents(os, tables_.f); - *os << "};\n" - "\n" - "} // namespace random_internal\n" - "ABSL_NAMESPACE_END\n" - "} // namespace absl\n" - "\n" - "// clang-format on\n" - "// END GENERATED CODE"; - *os << std::endl; -} - -} // namespace random_internal -ABSL_NAMESPACE_END -} // namespace absl - -int main(int, char**) { - std::cerr << "\nCopy the output to gaussian_distribution.cc" << std::endl; - absl::random_internal::TableGenerator generator; - generator.Print(&std::cout); - return 0; -} |