requirements

# Build & Core Dependencies (C++)
cmake>=3.5
gcc>=7.0 | clang>=5.0  # C++11 support required

# Python Testing & Plotting
python>=3.6
matplotlib>=3.0  # For frequency/impulse response plots
numpy>=1.15      # Numerical support for tests
scipy>=1.0       # Optional (for reference comparisons)

# QT5 for Demo Apps (Linux/macOS/Windows)
qt5-default       # Linux (Debian/Ubuntu)
pyqt5>=5.15       # Python bindings for QT apps
pyside2           # Alternative QT bindings (if preferred)

# Homebrew (macOS-only, handled separately)
# brew install qt5  # Manual step for macOS users

# Packaging (Debian/Ubuntu)
debhelper         # For .deb package generation
doxygen           # Documentation
```

---

### **Additional Setup Notes**:
1. **For Homebrew (macOS)**:
   ```bash
   brew install qt5 cmake
   ```
2. **For Ubuntu/Debian**:
   ```bash
   sudo apt-get install qt5-default cmake doxygen debhelper
   ```
3. **Python Virtual Environment** (recommended):
   ```bash
   python -m venv venv
   source venv/bin/activate  # Linux/macOS
   pip install -r requirements.txt
   ```

---

### **Key Dependencies Explained**:
- **C++11 Compiler**: Required for modern SPUCE features.
- **QT5**: Needed for the demo apps (`fir_plot`, `iir_plot`, etc.).
- **Python Libraries**: Used for testing/plotting filter responses.
- **Debian Packaging**: For `.deb` files (PPA releases).

---

### **Optional Extras**:
- **Eigen3** (for advanced linear algebra in C++ tests):
  ```plaintext
  libeigen3-dev>=3.3
  ```
- **Boost** (if older C++98 compatibility is needed):
  ```plaintext
  libboost-all-dev>=1.65
  ```