【matlab】频域滤波函数paddedsize

function PQ = paddedsize(AB,CD,~ )
%PADDEDSIZE Computes padded sizes useful for FFT-based filtering.
%   Detailed explanation goes here
if nargin == 1
PQ = 2*AB;
elseif nargin ==2 && ~ischar(CD)
PQ = QB +CD -1;
PQ = 2*ceil(PQ/2);
elseif nargin == 2
m = max(AB);%maximum dimension

%Find power-of-2 at least twice m.
P = 2^nextpow(2*m);
PQ = [P,P];
elseif nargin == 3
m = max([AB CD]);%maximum dimension
P = 2^nextpow(2*m);
PQ = [P,P];
else
error('Wrong number of inputs');

end