how to give a matrix index value from negative?

In my project handling some matrix form...but matrix starting index value as o..that is a[0] ,a[1] ...and so on. now i represent the value -4 to +4...how to represent (-4) in index form as a[..]????

Answer 1

[Andrei Bobrov]

a = -4:4;
a(1)

for prasanna comment

su=4;
sv=4;
fh=[1 2 3 4; 2 3 4 5 ; 5 6 7 8 ; 1 2 3 5];
t = -4:4;
n = numel(t);
a = ones(n);
for ii = 1:n
    for jj = 1:n  
        for u=1:su-2
            for v=1:sv
                 if fh(u,v)==t(ii) && fh(u+1,v)==t(jj)
                     dell=1;
                 else
                     dell=0;
                 end 
                 a(ii,jj)=a(ii,jj)+dell;
            end
        end
    end
end

[Dhines]

a(1) represents what?

[Dhines]

su=4;
sv=4;
fh=[1 2 3 4; 2 3 4 5 ; 5 6 7 8 ; 1 2 3 5];
for i=-4:4
    for j=-4:4   
        a(i,j)=1;
        for u=1:su-2
            for v=1:sv
                 if (fh(u,v)==i && fh(u+1,v)==j)
                     dell=1;
                 else
                     dell=0;
                 end 
                 a(i,j)=a(i,j)+dell;
            end
        end
    end
end

..when i run this code i got this error..

??? Attempted to access a(-4,-4); index must be a positive integer or logical.

Error in ==> testit at 6
        a(i,j)=1;

[Andrei Bobrov]

see my answer

[Dhines]

thank u very much sir..

[Dhines]

please give one suggestion sir,,, here su and sv ,i taken as a dimensions of original image ...my image is bmp type of image. size is 416x259...when i replace the value of su and sv on before coding session..what i have to do change in code?...su,sv,fh,t,n,a?

[Jan]

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