Matrix Sub Matrix Error

I want to place element of matrix g as g(11)=(a11+a12+a21+a22)/4 and for last column and last row I want to add g(n1)=(an1+a11+an2+a12)/4

m=[1:5;2:6;3:7;4:8;5:9;];

width=length(m(1,:)); g=zeros(width);

%% for a=1:width for b=1:width e=a+1; f=b+1; if ( e > width ) e=1; if ( f > width ) f=1; end end

          g(a,b) = (m(a,b)+m(e,b)+m(a, f)+m(e,f))/4;
        end
end
g

Showing error as ??? Attempted to access local_trandata(1,6); index out of bounds because size(local_trandata)=[5,5].

Please tell me how i can resolve this error.

Answer 1

[Andrei Bobrov]

width=length(m(1,:)); 
g=zeros(width);
for a=1:width 
    for b=1:width 
        e=a+1; 
        f=b+1; 
        if ( e > width ) 
            e=1; 
        end
        if ( f > width ) 
            f=1; 
        end
        g(a,b) = (m(a,b)+m(e,b)+m(a, f)+m(e,f))/4;
    end
end
g

OR

m1 = zeros(size(m)+1);
m1(1:end-1,1:end-1)=m;
m1(end,:) = m1(1,:);
m1(:,end) = m1(:,1);
g = conv2(m1,[1 1;1 1]*.25,'valid');

[Amit]

Thanks andrei