Undefined function or variable

function y = ratioimg(u)
[L2,num2]=bwlabel(u,8); %連通區域標記
B2=zeros(size(u));
for i=1:num2
    [r,c] = find(L2==i);  
    left(i)=min(c);
    right(i)=max(c);
    up(i)=min(r);
    down(i)=max(r);
     if ((down(i)-up(i))/(right(i)-left(i)))>0.8&((down(i)-up(i))/(right(i)-left(i)))<1
        [x,y]=find(L2==i);
        B2=B2+bwselect(u,y,x,8);%%%把滿足長寬比在0.8到2的區域留下
    end
end
y = B2;
end

i use this function on simulink simulation but show the error :

Undefined function or variable 'left'. The first assignment to a local variable determines its class.

Function 'MATLAB Function' (#35.120.124), line 6, column 5:
"left"
Launch diagnostic report.

how can i solve this problem!

Answer 1

[Jan]

You do not use left as a vector and it is not replied as output also. Then omit the "(i)":

function y = ratioimg(u)
[L2,num2] = bwlabel(u,8); %連通區域標記
y = zeros(size(u));  % Better than creating B2 and copy it to y
for i=1:num2
    [r,c] = find(L2==i);
    left  = min(c);
    right = max(c);
    up    = min(r);
    down  = max(r);
    d     = (down-up) / (right-left);
    if d > 0.8 & d < 1
        % [x,y]=find(L2==i);  % Done above already
        y = y + bwselect(u, c, r, 8); %%%把滿足長寬比在0.8到2的區域留下
    end
end
end

[tsai kai shung]

Thank you for your help