Address comments

CMakeLists.txt

@@ -16,7 +16,8 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 # Need to enforce -fPIC across whole project to build shared libraries
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
-# TODO different compilation flags for Debug/Release modes
+# TODO different compilation flags for Debug/Release modes; also pull in
+# target_compile_options for fast_pauli target defined below
 if(NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE Release)
 endif()

README.md

@@ -39,10 +39,17 @@ pre-commit install # installs the checks as pre-commit hooks
 
 ## Build and Test
 
+- Configure and build project:
 ```bash
 cmake -B build -DCMAKE_CXX_COMPILER=clang++
-cmake --build build
+cmake --build build --parallel
+```
+- Install compiled python module to `fast_pauli` directory:
+```bash
 cmake --install build
+```
+- Run C++ tests:
+```bash
 ctest --test-dir build
 ```
 

fast_pauli/cpp/include/__pauli_string.hpp

@@ -188,10 +188,10 @@ struct PauliString {
 
       T sign = diag(po) ? -1.0 : 1.0;
 
-      // TODO any benefit from defining 1UL << l in a const auto var?
-      for (size_t li = (1UL << l); li < (1UL << (l + 1)); li++) {
-        k[li] = k[li - (1UL << l)] + (1UL << l) * sign;
-        m[li] = m[li - (1UL << l)] * eps;
+      auto const lower_bound = 1UL << l;
+      for (size_t li = lower_bound; li < (lower_bound << 1); li++) {
+        k[li] = k[li - lower_bound] + lower_bound * sign;
+        m[li] = m[li - lower_bound] * eps;
       }
     }
   }

fast_pauli/cpp/src/CMakeLists.txt

@@ -4,8 +4,9 @@ file(GLOB FAST_PAULI_BINDINGS CONFIGURE_DEPENDS "*.cpp")
 find_package(pybind11 REQUIRED)
 
 # TODO use different set of parameters depending on CMAKE_BUILD_TYPE
-pybind11_add_module(_fast_pauli SHARED OPT_SIZE ${FAST_PAULI_BINDINGS})
+pybind11_add_module(_fast_pauli SHARED ${FAST_PAULI_BINDINGS})
 target_link_libraries(_fast_pauli PUBLIC fast_pauli)
+# TODO recheck from where it is pulling in numpy headers
 
 install(TARGETS _fast_pauli
         LIBRARY DESTINATION "${PROJECT_SOURCE_DIR}/fast_pauli")

fast_pauli/cpp/src/fast_pauli.cpp

@@ -9,29 +9,9 @@ namespace fp = fast_pauli;
 namespace py = pybind11;
 using namespace pybind11::literals;
 
-void scale_tensor_3d(py::array_t<double> array, double scale) {
-  auto arr = array.mutable_unchecked<>();
-  std::mdspan tensor(arr.mutable_data(), arr.shape(0), arr.shape(1),
-                     arr.shape(2));
-
-#pragma omp parallel for collapse(3)
-  for (size_t i = 0; i < tensor.extent(0); i++) {
-    for (size_t j = 0; j < tensor.extent(1); j++) {
-      for (size_t k = 0; k < tensor.extent(2); k++) {
-        tensor(i, j, k) *= scale;
-      }
-    }
-  }
-}
-
 PYBIND11_MODULE(_fast_pauli, m) {
   // TODO init default threading behaviour for the module
 
-  m.doc() = "Example NumPy/C++ Interface Using std::mdspan"; // optional module
-                                                             // docstring
-  m.def("scale_tensor_3d", &scale_tensor_3d, "Scale a 3D tensor by a scalar.",
-        py::arg().noconvert(), py::arg("scale"));
-
   py::class_<fp::Pauli>(m, "Pauli")
       .def(py::init<>())
       .def(py::init<int const>(), "code"_a)
@@ -100,4 +80,4 @@ PYBIND11_MODULE(_fast_pauli, m) {
            [](fp::PauliString const &self) { return fmt::format("{}", self); });
 
   py::class_<fp::SummedPauliOp<double>>(m, "SummedPauliOp").def(py::init<>());
-}
+}