Error Using cellfun for a Matrix

I have an 81 x 81 matrix that divided it into smaller matrices:

a = rand(81,81);
n = 3*ones(1,27);
a_d = mat2cell(a,n,n)

a_d = 27×27 cell array
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}
    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}    {3×3 double}

Now I want to perform this operation on each of the small matrices but it gives me error:

G_x = @(x) sum((x-a_d)./(x+a_d),'all'); 
B_x = cellfun(G_x,a_d)

Operator '-' is not supported for operands of type 'cell'.

Error in solution (line 4)
G_x = @(x) sum((x-a_d)./(x+a_d),'all');

Can someone please help me! Thank you.

Answer 1

[Simon Chan]

Try the following:

for r = 1:27
    for c = 1:27
        A = a_d{r,c};
        B_x{r,c} = cellfun(@(x) sum((x-A)./(x+A),'all'),num2cell(A));
    end
end

Answer 2

[Kevin Holly]

a = rand(81,81);
n = 3*ones(1,27);
a_d = mat2cell(a,n,n);
for i = 1:27
    for j = 1:27
G_x = @(x) sum((x-a_d{i,j})./(x+a_d{i,j}),'all'); 
B_x(i,j,:,:) = cellfun(G_x,a_d);
    end
end
size(B_x)

ans = 1×4

27 27 27 27

[MarshallSc]

Thank you sir, but the result (B_x) should give me a 27 x 27 cell instead of 1 x 4 double. The operation (sum of a normalized relationship between each point) does not change the size of the original cell (a_d).

[Kevin Holly]

FYI, braces needed to be added as Simon had done.

a = rand(81,81);
n = 3*ones(1,27);
a_d = mat2cell(a,n,n);
for i = 1:27
    for j = 1:27
G_x = @(x) sum((x-a_d{i,j})./(x+a_d{i,j}),'all'); 
B_x{i,j,:,:} = cellfun(G_x,a_d); %Added braces here
    end
end
size(B_x)

ans = 1×2

27 27