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function [xSfGridCyclesDeg,ySfGridCyclesDeg] = PositionGridMinutesToSfGridCyclesDeg(xGridMinutes,yGridMinutes)
%PositionGridMinutesToSfGridCyclesDeg Convert mesh sf coords to mesh position coords
% xSfGridCyclesDeg,ySfGridCyclesDeg] = PositionGridMinutesToSfGridCyclesDeg(xGridMinutes,yGridMinutes)
%
% Convert passed x,y position mesh grids in minutes to corresponding
% sf mesh grids in cycles/degree. Useful for psf/lsf/otf calculation
%% Generate spatial frequency grids
%
% Samples are evenly spaced and the same for both x and y (checked above).
% Handle even versus odd dimension properly for fft conventions.
[m,n] = size(xGridMinutes);
if (m ~= n)
error('Passed grids should be square');
end
centerPosition = floor(n/2) + 1;
spatialXExtentMinutes = xGridMinutes(centerPosition,end)-xGridMinutes(centerPosition,1);
spatialYExtentMinutes = yGridMinutes(end,centerPosition)-yGridMinutes(1,centerPosition);
if (spatialXExtentMinutes ~= spatialYExtentMinutes)
error('Spatial frequency extent not matched in x and y');
end
if (rem(n,2) == 0)
sfCyclesDeg = 60*(-n/2:n/2-1)/spatialXExtentMinutes;
else
sfCyclesDeg = 60*(-floor(n/2):floor(n/2))/spatialXExtentMinutes;
end
[xSfGridCyclesDeg,ySfGridCyclesDeg] = meshgrid(sfCyclesDeg,sfCyclesDeg);
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