scipycpp v1.0.0: header-only C++ scipy API based on numpcpp+Eigen3+pocketfft

Modules: stats, integrate, optimize, interpolate, signal, spatial,
special, linalg (Eigen3), fft (pocketfft).
36 bit-exact alignment tests passing (float64+float32).

Author: peng.li24

.github/ISSUE_TEMPLATE/bug_report.md

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+---
+name: Bug Report
+about: Report a bug in scipycpp
+title: "[Bug] "
+labels: bug
+assignees: ""
+---
+
+## Description
+
+A clear description of the bug.
+
+## Steps to Reproduce
+
+1.
+2.
+3.
+
+## Expected Behavior
+
+What should have happened.
+
+## Actual Behavior
+
+What actually happened, including any error messages.
+
+## Environment
+
+- OS: [e.g. Ubuntu 22.04]
+- Compiler: [e.g. GCC 12, Clang 16]
+- CMake version:
+- Python version:

.github/ISSUE_TEMPLATE/feature_request.md

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+---
+name: Feature Request
+about: Suggest a new feature or enhancement
+title: "[Feature] "
+labels: enhancement
+assignees: ""
+---
+
+## Problem
+
+What problem would this feature solve?
+
+## Proposed Solution
+
+Describe the feature or API you'd like to see.
+
+## Alternatives Considered
+
+Any alternative approaches you've thought about.
+
+## Additional Context
+
+Any other context, references, or use cases.

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push: { branches: [master], tags: ['v*'] }
+  pull_request: { branches: [master] }
+
+jobs:
+  test:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y python3 python3-pip python3-dev libeigen3-dev
+          pip3 install pybind11 numpy scipy pytest
+      - name: Build test module
+        run: make -C tests
+      - name: Run tests
+        run: make -C tests test
+
+  release:
+    if: startsWith(github.ref, 'refs/tags/v')
+    needs: test
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build .deb
+        run: mkdir build && cd build && cmake .. -DCMAKE_BUILD_TYPE=Release && make deb
+      - name: Publish
+        uses: softprops/action-gh-release@v2
+        with:
+          files: build/scipycpp-dev-*.deb
+          generate_release_notes: true
+        env: { GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}" }

.gitignore

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+# Build directories
+build/
+cmake-build-*/
+
+# Compiled output
+*.o
+*.so
+*.dylib
+*.dll
+*.a
+*.lib
+*.exe
+
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+.pytest_cache/
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+.DS_Store
+
+# CMake generated
+CMakeCache.txt
+CMakeFiles/
+cmake_install.cmake
+Makefile
+!tests/Makefile
+CTestTestfile.cmake
+compile_commands.json
+
+# Packaging
+*.deb
+*.rpm
+
+# CMake packaging artifacts (in-source builds)
+CPackConfig.cmake
+CPackSourceConfig.cmake
+_CPack_Packages/
+install_manifest.txt
+scipycpp-config-version.cmake
+scipycpp-config.cmake

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.16)
+project(scipycpp VERSION 1.0.0 LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+# ---- INTERFACE target for find_package consumers ----------------------------
+add_library(scipycpp INTERFACE)
+target_include_directories(scipycpp INTERFACE
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+    $<INSTALL_INTERFACE:include/scipycpp>
+)
+target_compile_features(scipycpp INTERFACE cxx_std_17)
+
+# Transitive dependencies: scipycpp → pocketfft, Eigen3, numpcpp
+target_link_libraries(scipycpp INTERFACE
+    pocketfft::pocketfft
+    Eigen3::Eigen
+    numpycpp::numpycpp
+)
+
+# ---- Install — header-only C++ library --------------------------------------
+install(DIRECTORY scipy
+    DESTINATION include/scipycpp
+    FILES_MATCHING PATTERN "*.h"
+)
+install(DIRECTORY pycpp
+    DESTINATION include/scipycpp
+    FILES_MATCHING PATTERN "*.h"
+    PATTERN ".pytest_cache" EXCLUDE
+)
+
+include(CMakePackageConfigHelpers)
+configure_package_config_file(
+    scipycpp-config.cmake.in
+    ${CMAKE_CURRENT_BINARY_DIR}/scipycpp-config.cmake
+    INSTALL_DESTINATION lib/cmake/scipycpp
+)
+write_basic_package_version_file(
+    ${CMAKE_CURRENT_BINARY_DIR}/scipycpp-config-version.cmake
+    VERSION ${PROJECT_VERSION}
+    COMPATIBILITY SameMajorVersion
+)
+install(FILES
+    ${CMAKE_CURRENT_BINARY_DIR}/scipycpp-config.cmake
+    ${CMAKE_CURRENT_BINARY_DIR}/scipycpp-config-version.cmake
+    DESTINATION lib/cmake/scipycpp
+)
+
+# ---- Docs & examples -------------------------------------------------------
+install(FILES README.md DESTINATION share/scipycpp)
+install(DIRECTORY example/ DESTINATION share/scipycpp/example)
+
+# ---- CPack DEB packaging ----------------------------------------------------
+set(CPACK_PACKAGE_NAME                     "scipycpp-dev")
+set(CPACK_PACKAGE_VERSION                  ${PROJECT_VERSION})
+set(CPACK_PACKAGE_VENDOR                   "array2d")
+set(CPACK_PACKAGE_CONTACT                  "array2d")
+set(CPACK_PACKAGE_DESCRIPTION_SUMMARY      "C++ header-only scipy API — based on numpcpp+Eigen3+pocketfft")
+set(CPACK_GENERATOR                        "DEB")
+set(CPACK_DEB_COMPONENT_INSTALL            OFF)
+set(CPACK_DEBIAN_PACKAGE_MAINTAINER        "array2d")
+set(CPACK_DEBIAN_PACKAGE_SECTION           "libdevel")
+set(CPACK_DEBIAN_PACKAGE_PRIORITY          "optional")
+set(CPACK_DEBIAN_FILE_NAME                 "scipycpp-dev-${CPACK_PACKAGE_VERSION}-Linux.deb")
+set(CPACK_PACKAGING_INSTALL_PREFIX         "/usr")
+
+# Recommend the required dependencies
+set(CPACK_DEBIAN_PACKAGE_DEPENDS "numpycpp-dev, libeigen3-dev, pocketfft-dev")
+
+include(CPack)
+add_custom_target(deb COMMAND cpack -G DEB
+    COMMENT "Packaging scipycpp-dev-${CPACK_PACKAGE_VERSION}-Linux.deb")
+
+message(STATUS "scipycpp v${PROJECT_VERSION}  (header-only C++ library)")
+message(STATUS "  Dependencies: numpcpp + Eigen3 + pocketfft")
+message(STATUS "  DEB:  make deb  →  scipycpp-dev-${CPACK_PACKAGE_VERSION}-Linux.deb")
+message(STATUS "  Test: cd tests/ && make  →  build + run alignment tests")

README.md

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+# scipycpp
+
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+[![C++17](https://img.shields.io/badge/C%2B%2B-17-blue.svg)](https://en.cppreference.com/w/cpp/17)
+
+## Overview
+
+`scipycpp` is a **header-only C++ library** implementing scipy's core APIs with
+**bit-level precision alignment** against Python scipy.
+
+Built on proven C++ libraries:
+- **[numpycpp](https://github.com/array2d/numpycpp)** — numpy primitives + SVML bridge
+- **[Eigen3](https://eigen.tuxfamily.org/)** — linear algebra (solve, inv, det, eig, svd, cholesky)
+- **[pocketfft](https://github.com/mreineck/pocketfft)** — FFT (same library numpy/scipy use internally)
+
+## Quick Start
+
+```cpp
+#include "scipy/core.h"
+
+// Integration
+auto [val, err] = scipy::integrate::quad([](double x){ return x*x; }, 0.0, 4.0);
+
+// Stats
+std::vector<double> pdf(3);
+scipy::stats::norm_pdf(data, pdf.data(), 3);
+
+// Linalg (Eigen3-backed)
+double A[4] = {2,1,1,3}, b[2] = {5,6}, x[2];
+scipy::linalg::solve(A, x, b, 2);
+
+// FFT (pocketfft-backed — same as numpy/scipy)
+scipy::fft::fft(signal, spectrum, 4);
+```
+
+### Dependencies
+
+```bash
+# Install dependencies
+sudo dpkg -i numpycpp-dev-*.deb
+sudo apt-get install libeigen3-dev
+sudo dpkg -i pocketfft-dev-*.deb
+
+# Install scipycpp
+mkdir build && cd build
+cmake .. && make deb
+sudo dpkg -i scipycpp-dev-*.deb
+```
+
+```cmake
+find_package(scipycpp REQUIRED)
+target_link_libraries(myapp PRIVATE scipycpp::scipycpp)
+```
+
+## Modules
+
+| Module | Backend | Key APIs |
+|--------|---------|----------|
+| `integrate` | numpcpp + pure C++ | quad, simpson, trapezoid |
+| `optimize` | pure C++ | minimize_scalar (Brent), root_scalar |
+| `interpolate` | pure C++ | interp1d, CubicSpline |
+| `signal` | numpcpp | convolve, correlate |
+| `stats` | **numpycpp SVML** | norm.pdf/cdf/ppf (bit-exact) |
+| `spatial` | pure C++ | euclidean, cosine, manhattan, KDTree |
+| `special` | C++17 std | erf, gamma, beta, digamma, logsumexp |
+| `linalg` | **Eigen3** | solve, inv, det, eigvalsh, cholesky, svd |
+| `fft` | **pocketfft** | fft, ifft, rfft, irfft |
+
+## Testing
+
+```bash
+cd tests && make && make test
+```
+
+## License
+
+MIT

bench/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.16)
+project(scipycpp-bench LANGUAGES CXX)
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+include(FetchContent)
+FetchContent_Declare(googlebench
+    GIT_REPOSITORY https://github.com/google/benchmark.git
+    GIT_TAG v1.8.3
+)
+set(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "" FORCE)
+FetchContent_MakeAvailable(googlebench)
+
+add_executable(bench_core bench_core.cpp)
+target_include_directories(bench_core PRIVATE ..)
+target_link_libraries(bench_core PRIVATE benchmark::benchmark)

bench/bench_core.cpp

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+#include "scipy/core.h"
+#include <benchmark/benchmark.h>
+#include <vector>
+#include <random>
+
+static void BM_trapezoid(benchmark::State& state) {
+    size_t n = state.range(0);
+    std::vector<double> y(n);
+    std::mt19937 rng(42);
+    std::uniform_real_distribution<double> dist(1.0, 100.0);
+    for (size_t i = 0; i < n; ++i) y[i] = dist(rng);
+    for (auto _ : state) {
+        double r = scipy::integrate::trapezoid(y.data(), n);
+        benchmark::DoNotOptimize(r);
+    }
+    state.SetItemsProcessed(state.iterations() * n);
+}
+BENCHMARK(BM_trapezoid)->Range(1<<10, 1<<20);
+
+static void BM_normpdf(benchmark::State& state) {
+    size_t n = state.range(0);
+    std::vector<double> x(n), r(n);
+    std::mt19937 rng(42);
+    std::normal_distribution<double> dist(0.0, 1.0);
+    for (size_t i = 0; i < n; ++i) x[i] = dist(rng);
+    for (auto _ : state) {
+        scipy::stats::norm_pdf(x.data(), r.data(), n);
+        benchmark::DoNotOptimize(r.data());
+    }
+    state.SetItemsProcessed(state.iterations() * n);
+}
+BENCHMARK(BM_normpdf)->Range(1<<10, 1<<20);
+BENCHMARK_MAIN();

example/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.16)
+project(scipycpp_example LANGUAGES CXX)
+find_package(scipycpp REQUIRED)
+find_package(numpycpp REQUIRED)
+find_package(Eigen3 REQUIRED)
+find_package(pocketfft REQUIRED)
+add_executable(example main.cpp)
+target_link_libraries(example PRIVATE scipycpp::scipycpp numpycpp::numpycpp Eigen3::Eigen pocketfft::pocketfft)

example/main.cpp

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+#include <scipy/core.h>
+#include <iostream>
+#include <vector>
+#include <complex>
+
+int main() {
+    // --- Integration ---
+    std::vector<double> y = {0.0, 1.0, 4.0, 9.0, 16.0};
+    std::cout << "trapezoid: " << scipy::integrate::trapezoid(y.data(), y.size()) << std::endl;
+    std::cout << "simpson:   " << scipy::integrate::simpson(y.data(), nullptr, y.size()) << std::endl;
+
+    auto [val, err] = scipy::integrate::quad([](double x) { return x * x; }, 0.0, 4.0);
+    std::cout << "quad(x^2, 0,4): " << val << " (err=" << err << ")" << std::endl;
+
+    // --- Stats ---
+    std::vector<double> x = {-1.0, 0.0, 1.0};
+    std::vector<double> pdf(3);
+    scipy::stats::norm_pdf(x.data(), pdf.data(), 3);
+    std::cout << "norm.pdf: " << pdf[0] << " " << pdf[1] << " " << pdf[2] << std::endl;
+
+    // --- Linalg ---
+    double A[4] = {2.0, 1.0, 1.0, 3.0};
+    double b[2] = {5.0, 6.0};
+    double xs[2];
+    scipy::linalg::solve(A, xs, b, 2);
+    std::cout << "solve: x=[" << xs[0] << ", " << xs[1] << "]" << std::endl;
+
+    // --- FFT ---
+    std::vector<std::complex<double>> sig = {{1,0}, {2,0}, {3,0}, {4,0}};
+    std::vector<std::complex<double>> spec(4);
+    scipy::fft::fft(sig.data(), spec.data(), 4);
+    std::cout << "fft:";
+    for (auto& v : spec) std::cout << " (" << v.real() << "," << v.imag() << ")";
+    std::cout << std::endl;
+
+    return 0;
+}