pytorch

1588ea0d - Added log1p for complex in c10 (#89214)

Added log1p for complex in c10 (#89214) One PR towards #89205. The content is mostly from PR #38465, but slightly changed the expression to make it faster. Here are some benchmarking code: ```c++ #include <complex> #include <iostream> #include <chrono> // main.cc template<typename T> inline std::complex<T> log1p_v0(const std::complex<T> &z) { // this PR T x = z.real(); T y = z.imag(); T theta = std::atan2(y, x + T(1)); T r = x * (x + T(2)) + y * y; return {T(0.5) * std::log1p(r), theta}; } template<typename T> inline std::complex<T> log1p_v1(const std::complex<T> &z) { // PR #38465 T x = z.real(); T y = z.imag(); std::complex<T> p1 = z + T(1); T r = std::abs(p1); T a = std::arg(p1); T rm1 = (x * x + y * y + x * T(2)) / (r + 1); return {std::log1p(rm1), a}; } template<typename T> inline std::complex<T> log1p_v2(const std::complex<T> &z) { // naive, but numerically inaccurate return std::log(T(1) + z); } int main() { int n = 1000000; std::complex<float> res(0.0, 0.0); std::complex<float> input(0.5, 2.0); auto start = std::chrono::system_clock::now(); for (int i = 0; i < n; i++) { res += log1p_v0(input); } auto end = std::chrono::system_clock::now(); auto elapsed = end - start; std::cout << "time for v0: " << elapsed.count() << '\n'; start = std::chrono::system_clock::now(); for (int i = 0; i < n; i++) { res += log1p_v1(input); } end = std::chrono::system_clock::now(); elapsed = end - start; std::cout << "time for v1: " << elapsed.count() << '\n'; start = std::chrono::system_clock::now(); for (int i = 0; i < n; i++) { res += log1p_v2(input); } end = std::chrono::system_clock::now(); elapsed = end - start; std::cout << "time for v2: " << elapsed.count() << '\n'; std::cout << res << '\n'; } ``` Compiling the script with command `g++ main.cc` produces the following results: ``` time for v0: 237812271 time for v1: 414524941 time for v2: 360585994 ``` Pull Request resolved: https://github.com/pytorch/pytorch/pull/89214 Approved by: https://github.com/lezcano