extract_oversampled

ska_sdp_func_python.fourier_transforms.fft_support.extract_oversampled(a, xf, yf, kernel_oversampling, kernelwidth)

Extract the (xf-th,yf-th) w-kernel from the oversampled parent.

Offsets are suitable for correcting of fractional coordinates, e.g. an offset of (xf,yf) results in the kernel for an (-xf,-yf) sub-grid offset.

We do not want to make assumptions about the source grid’s symmetry here, which means that the grid’s side length must be at least \(kernel_oversampling*(npixel+2)\) to contain enough information in all circumstances.

Parameters:

• a – grid from which to extract

• xf – Offset in x

• yf – Offset in y

• kernel_oversampling – oversampling factor

• kernelwidth – size of section