fftvis: A Non-Uniform Fast Fourier Transform-based Visibility Simulator

fftvis is a fast Python package designed for simulating interferometric visibilities using the Non-Uniform Fast Fourier Transform (NUFFT). It provides a convenient and efficient way to generate simulated visibilities.

Features

• Utilizes the Flatiron Institute NUFFT (finufft) algorithm for fast visibility simulations that agree with similar methods (matvis) to high precision.
• Designed to be a near drop-in replacement to matvis with a ~10-100x improvement in runtime
• Extensible design that allows for easy addition of new backends
• Support for polarized beam patterns and polarized sky models
• Support for per-antenna beams w/ functionality to support representing per-antenna beams with a linear basis. See the example notebook for details.

Current Limitations

• GPU backend exists only as a stub implementation (coming soon!)
• Diffuse sky models must be pixelized

Installation

You can install fftvis via pip:

pip install fftvis

Basic Usage

from fftvis import simulate_vis

# Simulate visibilities with the CPU backend (default)
vis = simulate_vis(
    ants=antenna_positions,
    fluxes=source_fluxes,
    ra=source_ra,
    dec=source_dec,
    freqs=frequencies,
    times=observation_times,
    beam=beam_model,
    polarized=True,
    backend="cpu"  # Use "gpu" for GPU acceleration when implemented
)

Architecture

fftvis is structured with a modular design:

• Core: Contains abstract interfaces and base classes that define the API
• CPU: Contains the CPU-specific implementation
• GPU: Contains the GPU implementation (currently stubbed for future development)
• Wrapper: Provides a high-level API for backward compatibility

This modular design makes the package more maintainable and extensible, allowing for the addition of new backends and optimizations without affecting the user API.

Contributing

Contributions to fftvis are welcome! If you find any issues, have feature requests, or want to contribute improvements, please open an issue or submit a pull request on the GitHub repository: fftvis on GitHub

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

This package relies on the finufft implementation provided by finufft library. Special thanks to the contributors and maintainers of open-source libraries used in this project.

Citation

If you use fftvis in your research, please cite our paper published in RAS Techniques and Instruments:

fftvis: a non-uniform Fast Fourier Transform based interferometric visibility simulator Tyler A. Cox, Steven G. Murray, Aaron R. Parsons, Joshua S. Dillon, Kartik Mandar, Zachary E. Martinot, Robert Pascua, Piyanat Kittiwisit, and James E. Aguirre.
RAS Techniques and Instruments, Volume 4, 2025, rzaf056.
DOI: 10.1093/rasti/rzaf056 | arXiv: 2506.02130

BibTeX

@article{2025RASTI...4af056C,
  author        = {Cox, Tyler A. and Murray, Steven G. and Parsons, Aaron R. and Dillon, Joshua S. and Mandar, Kartik and Martinot, Zachary E. and Pascua, Robert and Kittiwisit, Piyanat and Aguirre, James E.},
  title         = "{fftvis: a non-uniform Fast Fourier Transform based interferometric visibility simulator}",
  journal       = {RAS Techniques and Instruments},
  year          = {2025},
  month         = {jan},
  volume        = {4},
  pages         = {rzaf056},
  doi           = {10.1093/rasti/rzaf056},
  archivePrefix = {arXiv},
  eprint        = {2506.02130},
  primaryClass  = {astro-ph.IM},
  adsurl        = {https://ui.adsabs.harvard.edu/abs/2025RASTI...4af056C}
}