HOW CAN I WRITE THE INVERSE FUNCTION OF PERIODIC PLUS SMOOTH DECOMPOSITION. I HAVE TAKEN A 360*360 MATRIX AND DIVIDED IT INTO 90 BLOCKS THEN PERFORMED DECOMPOSITION ON EACH

function [p1,s] = perdm_fun(b)

[ny,nx] = size(b);

b = double(b);

X = 1:nx; Y = 1:ny;

v = zeros(ny,nx);

v(1,X) = b(1,X)-b(ny,X);

v(ny,X) = -v(1,X);

v(Y,1 ) = v(Y,1 )+b(Y,1)-b(Y,nx);

v(Y,nx) = v(Y,nx)-b(Y,1)+b(Y,nx);

fx = repmat(cos(2.*pi*(X -1)/nx),ny,1);

fy = repmat(cos(2.*pi*(Y'-1)/ny),1,nx);

fx(1,1)=0.; % avoid division by 0 in the line below

s = real(ifft2(fft2(v)*0.5./(2.-fx-fy)));

p = b-s;

%pmod = reshape(p.',1,[]);

%list=knuthShuffle(pmod);

%p1=reshape(list,4,4);

I want to perform inverse decomposition and get blocks as output...As i am a new comer in this field i can't find any way. hope to get help. I am getting b from this code:

mat=4*ones(1,90);

newRow = zeros(1,size(F3,2));

newF3 = [F3(1:359, :); newRow; F3(360:end, :)];

H=mat2cell(newF3,mat,mat);

%for i=1:90

%M=cellfun(@str2double, H);

%end

for i=1:90

for j=1:90

celmat=zeros(4);

b=(H{i,j});

% bmod = reshape(b.',1,[]);

% list=knuthShuffle(bmod);

% b1=reshape(list,4,4);

[p,s] = perdm_fun(b); end

end