First commit

Author: robertodr

.envrc

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+case $HOSTNAME in
+  (minazo)
+     use nix '<nixpkgs>' -A dev-shells.mrchem
+     ;;
+  (*)
+     ;;
+esac
+#layout pipenv

.gitignore

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+build*
+install*
+debug*
+.idea
+.ipynb_checkpoints
+*.ipynb
+*.swp
+cmake-build-debug

CMakeLists.txt

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+# define minimum cmake version
+cmake_minimum_required(VERSION 3.11 FATAL_ERROR)
+
+# project name and supported language
+project(ompybind11 LANGUAGES CXX)
+
+# require C++11
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_EXTENSIONS OFF)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+option(ENABLE_OPENMP "Use OpenMP parallelization" OFF)
+
+# for testing we will need the python interpreter
+find_package(PythonInterp REQUIRED)
+
+add_subdirectory(ompybind11)
+
+# turn on testing
+enable_testing()
+
+# define test
+add_test(
+  NAME
+    python_test
+  COMMAND
+    ${CMAKE_COMMAND} -E env OMPYBIND11_MODULE_PATH=$<TARGET_FILE_DIR:ompybind11>
+    ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/ompybind11/test.py
+  )

ompybind11/CMakeLists.txt

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+include(FetchContent)
+
+FetchContent_Declare(
+  pybind11_sources
+  GIT_REPOSITORY https://github.com/pybind/pybind11.git
+  GIT_TAG        v2.2
+)
+
+FetchContent_GetProperties(pybind11_sources)
+
+if(NOT pybind11_sources_POPULATED)
+  FetchContent_Populate(pybind11_sources)
+
+  add_subdirectory(
+    ${pybind11_sources_SOURCE_DIR}
+    ${pybind11_sources_BINARY_DIR}
+    )
+endif()
+
+if(ENABLE_OPENMP)
+  find_package(OpenMP REQUIRED)
+endif()
+
+# create python module
+add_library(ompybind11
+  MODULE
+    ompybind11.cpp
+  )
+
+target_link_libraries(ompybind11
+  PUBLIC
+    pybind11::module
+    $<$<AND:$<BOOL:ENABLE_OPENMP>,$<BOOL:OpenMP_FOUND>>:OpenMP::OpenMP_CXX>
+  )
+
+set_target_properties(ompybind11
+  PROPERTIES
+    PREFIX "${PYTHON_MODULE_PREFIX}"
+    SUFFIX "${PYTHON_MODULE_EXTENSION}"
+  )

ompybind11/ompybind11.cpp

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+#include <functional>
+#include <iostream>
+
+#include <omp.h>
+
+#include <pybind11/functional.h>
+#include <pybind11/pybind11.h>
+
+namespace py = pybind11;
+
+double eval_func(int rank, std::function<double(double)> func, double x) {
+  double out = 0.0;
+#pragma omp parallel shared(out)
+  {
+    int thread_num = omp_get_thread_num();
+    if (thread_num == rank) {
+      std::cout << "Thread " << thread_num << " working\n";
+      out = func(x);
+    }
+  }
+  return out;
+}
+
+double calc_pi(int n) {
+  double step = 1.0 / n;
+  double s = 0.0;
+
+#pragma omp parallel
+  {
+    double x;
+#pragma omp for reduction(+ : s)
+    for (int i = 0; i < n; i++) {
+      x = (i + 0.5) * step;
+      s += 4.0 / (1 + x * x);
+    }
+  }
+  return step * s;
+};
+
+PYBIND11_MODULE(ompybind11, m) {
+  m.def("eval_func", &eval_func, py::arg("rank"), py::arg("function"),
+        py::arg("x"))
+      .def("calc_pi", [](int n) {
+        return calc_pi(n);
+      });
+}

ompybind11/test.py

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+import os
+import sys
+
+sys.path.append(os.getenv('OMPYBIND11_MODULE_PATH'))
+import ompybind11 # isort:skip
+
+
+def f(x):
+    return x*x
+
+x = 2.0
+
+pi = ompybind11.calc_pi(100)
+print('pi is {}'.format(pi))
+
+foo = ompybind11.eval_func(0, f, x)
+print('Output of eval_func {}\n'.format(foo))
+
+bar = ompybind11.eval_func(1, f, x)
+print('Output of eval_func {}\n'.format(bar))