BaseParameters

class ska_sdp_exec_swiftly.fourier_transform.algorithm_parameters.BaseParameters(**fundamental_constants)

Bases: object

**fundamental_constants contains the following keys:

Parameters:

• W – PSWF (prolate-spheroidal wave function) parameter (grid-space support)

• fov – field of view

• N – total image size

• Nx – subgrid spacing: subgrid offsets need to be divisible by Nx

• yB_size – effective facet size

• yP_size – padded facet size (pad facet with zeros at margins to reach this size)

• xA_size – effective subgrid size

• xM_size – padded subgrid size (pad subgrid with zeros at margins to reach this size)

• yN_size – padded facet size which evenly divides the image size, used for resampling facets into image space

A / x –> grid (frequency) space; B / y –> image (facet) space

The class, in addition, derives the following, commonly used sizes (integers), and offset arrays:

Parameters:

• xM_yP_size – (padded subgrid size * padded facet size) / N

• xM_yN_size – (padded subgrid size * padding) / N

• xMxN_yP_size – length of the region to be cut out of the prepared facet data (i.e. len(facet_m0_trunc), where facet_m0_trunc is the mask truncated to a facet (image space))

• xN_yP_size – remainder of the padded facet region after the cut-out region has been subtracted of it i.e. xMxN_yP_size - xM_yP_size

• nsubgrid – number of subgrids

• nfacet – number of facets

• facet_off – facet offset (numpy array)

• subgrid_off – subgrid offset (numpy array)

Methods Summary

calculate_facet_off()	Calculate facet offset array
calculate_subgrid_off()	Calculate subgrid offset array
check_params()	Validate some of the parameters.

Methods Documentation

calculate_facet_off()

Calculate facet offset array

calculate_subgrid_off()

Calculate subgrid offset array

check_params()

Validate some of the parameters.