我试图计算一个数组的FFT，但我得到一个错误：* “数组大小不兼容”*。如何解决这个问题？下面是我的代码：

% Read the image
im = imread('image2.jpg');

% Convert the image to double precision
im = im2double(im);

% Compute the FFT of the image
F = fft2(im);

% Define the filter mask
mask = [-1 -1 -1; -1 8 -1; -1 -1 -1];

% Filter the FFT using the mask
F_filtered = F .* fftshift(mask);

% Display the magnitude of the filtered FFT
imshow(log(abs(fftshift(F_filtered))), []); 

this error is coming 
Arrays have incompatible sizes for this operation.

Error in task3 (line 32)
F_filtered = F .* fftshift(mask);