Setup to Interface C++ with Python scripts 
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Last revised by S. Pattamudu-Manoharan on 2025 FEB 4

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Mac Setup Guide
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1. **Check if Clang is already installed**
   * Run the following command: ``clang --version``

   * If Clang is installed, it will display the version details.
   * If not, proceed to the installation steps below.

   **Install Clang**
   * Install Xcode Command Line Tools (which include Clang) by running: ``xcode-select --install``
   * Follow the on-screen instructions to complete the installation.

   **Verify Installation**
   * After installation, check if Clang is properly installed: ``clang --version``
   * This should display the Clang version.

2. **Install Required Python Packages to interface with C++**
   * Install `setuptools`, `wheel`, and `pybind11`: ``pip install setuptools wheel pybind11``

3. **Install Eigen**
   * Install Eigen using Homebrew: ``brew install eigen``

4. **Verify Eigen Installation**
   * Run: ``brew list eigen``
   * Copy the path that contains the ``include`` folder.

5. **Update Setup.py file**
   * Paste the copied Eigen path into the ``setup.py`` file.

6. **Build the Python Package**
   * Run: ``python setup.py build``

7. **Add the C++ build files path to your environment, follow these steps:** 
   Append the following line to your Bash profile configuration file:

   .. warning::
      **Avoid exposing sensitive information** when sharing your screen.  
      The command ``nano ~/.bash_profile`` opens a file that may contain credentials, API keys, or environment variables.  

   * To open the .bash_profile, run: ``nano ~/.bash_profile``

   * Add the following line: ``export PYTHONPATH='$PYTHONPATH:/your_cpp_build_path'``
     Update 'your_cpp_build_path' with the path of the directory that contains the compiled .so files.

     Click on control + X and then Y to save and exit the file.

   * Apply the changes by running this command: ``source ~/.bash_profile``

8. **Run the Python Test Code**
   * Finally, execute the test script ``"CPP_setup_verification.py"`` to verify the setup.

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Windows Setup Guide
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1. **Install C++ Build Tools for Visual Studio**
   * Download and install from `https://visualstudio.microsoft.com/downloads/?q=build+tools`

   * During installation, ensure to select **"C++ Development"** from the available options.
   * This will download and install the necessary components, approximately **6.7GB** in size.
   * These tools are required for building and compiling C++ extensions.


2. **Install Required Python Packages**
   * Run the following command: ``pip install setuptools wheel``

3. **C++ Extension Configuration**

   **Download Eigen**  
   * Get the latest version from: `https://eigen.tuxfamily.org/dox/GettingStarted.html`

   **Store Eigen in a Safe Location**  
   * Extract and place it in a secure directory, such as: ``C:\Program Files\Eigen``
     
   **Set the Eigen Path in Environment Variables**  
   * Add the Eigen include directory to the environment variable:

   **Include Eigen Directory in the Setup.py file**
   * ``eigen_include_dir = "C:\your_eigen_folder_path"``

4. **Set the C++ Build Path in Environment Variables**  
   * Add the C++ build path to the environment variable: ``C:Users/your_build_path/``

5. **Build the Python Package**
   * Run: ``bash python setup.py build``

6. **Run the Python Test Code**
   * Finally, execute the ``cpp_test.py`` script to verify the setup.