Create converging gratings in matlab

I have created square gratings and can move them left or right with the following code. However I want to move the grating in a converging direction that is both sides, left and right more towards the center. How can I modify the code to do that?

sf=6;

n=50;

for i=1:n

x=linspace(-pi, pi, 100);

sinewave=[];

sinewave=square((x*sf)+i); % -i for the other direction

onematrix=ones(size(sinewave));

sinewave2D=(onematrix' * sinewave);

colormap(gray);

imagesc(sinewave2D);

drawnow;

end

Thanks

Answer 1

[VINAYAK LUHA]

Hi Mohini,

It is my understanding that you want to know the modifications required in your code to make your gratings converge towards the center.

Here is a modification which involves decreasing the spatial frequency of the square wave in your code by modifying its frequency parameter as shown below:

F = (x * (sf - i/2));

Here is the complete code for your reference:

sf = 100;
n = 50;
for i = 1:n
    x = linspace(-pi, pi, 100);
    sinewave = [];
    sinewave = square((x * (sf - i/2))); 
    onematrix = ones(size(sinewave));
    sinewave2D = onematrix' * sinewave;
    colormap(gray);
    imagesc(sinewave2D);
    drawnow;
end

Hope this helps.

Regards,

Vinayak Luha