The left and right sides have a different number of elements

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Matthew Worker on 30 Nov 2021
Edited: John Kelly on 8 Dec 2021
this is my code and
%% 3. Fourier descriptor
%① Make the matrix above.
%Find the positions (x1, x2) of foreground pixels valued '1' and save them to ‘pos’ array.
input=[0 0 0 0 0 0 0; 0 0 0 1 0 0 0; 0 0 1 0 1 0 0; 0 1 0 0 0 1 0; 0 0 1 0 1 0 0; 0 0 0 1 0 0 0; 0 0 0 0 0 0 0];
pos=boundary4(input);
%② Make a vector ‘comp’ that contains complex numbers:
%real value: x1 of an element of ‘pos’,imaginary value: x2 of an element of ‘pos’.
comp=complex(pos(:,1),pos(:,2));
%③ Do Fourier transform with ‘comp’ and save the result to ‘ft’.
ft=fft(comp);
%Make zero vector ‘ft1’ which has same size of ‘ft’ and save only first and second element value of ‘ft’ to ‘ft’1.
ft1=zeros(size(ft));
ft1(1:2) =ft(1:2);
%④ Do inverse transform of ‘ft1’ and display the results by plotting imaginary numbers.
figure
subplot(1,2,1);
plot(input), axis ([1,14,1,14]), axis square
title('input');
subplot(1,2,2);
plot(ifft (ft1),'o'), axis ([1,14,1,14]), axis square
title('output');
this is the fxn to get the boundary
function out=boundary4(image)
n=[0 1;-1 0;0 -1;1 0];
flag=1;
cc=[];
[x,y]=find(image==1);
x=min(x);
imx=image(x,:);
y=min(find(imx==1));
first=[x y];
dir=3;
while flag==1
tt=zeros(1,4);
newdir=mod(dir+3,4);
for i=0:3
j=mod(newdir+i,4)+1;
tt(i+1)=image(x+n(j,1),y+n(j,2));
end
d=min(find(tt==1));
dir=mod(newdir+d-1,4);
x=x+n(dir+1,1);y=y+n(dir+1,2);
cc=[cc;x y];
if x==first(1)&y==first(2)
flag=0;
end
end
out =cc;
and i get this error
Unable to perform assignment because the left and right sides have a different number of elements.
Error in boundary4 (line 19)
tt(i+1)=image(x+n(j,1),y+n(j,2));
Error in script (line 57)
pos=boundary4(input);
Rena Berman on 8 Dec 2021

VBBV on 30 Nov 2021
Edited: VBBV on 30 Nov 2021
tt(:,i+1)=image(x+n(j,1),y+n(j,2))
Change this line to above

R2021a

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