Backend (CPU or GPU) and FFT Engine

NDArray Backend Selection

You can switch between NumPy (CPU) and CuPy (GPU) at runtime. The active array backend is exposed as xp for convenient use in your own code.

NumPy backend (CPU):

import xpunwrap

xpunwrap.set_ndarray_backend("numpy")  # "numpy" is the default anyway
xp = xpunwrap.get_ndarray_backend()
xp.array(...)  # will create a numpy array that exists on the CPU

CuPy backend (GPU):

import xpunwrap

xpunwrap.set_ndarray_backend("cupy")
xp = xpunwrap.get_ndarray_backend()
xp.array(...)  # will create a cupy array that exists on the GPU

Fourier Transform (FFT) Engine Selection

xpUnwrap also follows the qpretrieve and nrefocus packages by having multiple packages available for performing Fourier transforms. These are handled automatically in the background. See the example using_backends_and_fft-engines.py for more details.

• For CPU NumPy and PyFFTW (optional dependency) are available. PyFFTW is preferred internally, but if not installed xpUnwrap will fall-back to NumPy.

• For GPU CuPy is used. CuPy is an optional dependency and the installed CuPy version should match your CUDA version.

See the installation section for how to install the optional dependencies.