function sinewave2D = MakeSineApertureInput (xval, sf)

% function that creates a vertical sinewave windowed by a circular aperture
%
% Inputs:
%   xval: for which the sinusoids is computed
%   sf:   the saptial frequecy of the sinusoid
%   radius: the radiusl of the aperture in pixels
% Outputs: a 2D sinusoidal grating image

radius=input('please input the radius: ');
if isempty(radius)
    radius=3;
end

onematrix=ones(size(xval));
sinewave=sin(xval*sf);
sinewave2D=(onematrix'*sinewave);
for r=1:length(xval)
    for c=1:length(xval)
        if xval(r).^2+xval(c).^2>radius^2
            sinewave2D(r,c)=0;
        end
    end
end