MATLAB: How to solve, index exceeds matrix dimensions

Question

The error appears in this line(fprintf('\t%d',c1(o)))

Answer 1

The code that contains the problem is copied below from your pdf attachment. The error happens when 'o' becomes larger than the number of elements in 'c1'.

while(o<=over)
    fprintf('\t%d',c1(o));
    o=o+1;
end

The while-loop that comes before this only has 1 iteration because of the break at the end! Without the break, the while loop will never end because 'o' will always be 1 since you are not increasing that value within the loop.

Solution

This is how your last 2 while-loops should appear. The arrows show where I corrected your code.

while(o<=over);
    m=m1(o);
    diff=0;
    if(m>n);
        diff=m-n+1;
    end
    m=m-diff;
    
    qm=dec2bin(e);
    len=length(qm);
    c=1;
    xz=1;
    while(xz<=len)
        if(qm(xz)=='1')
            c=mod(mod((c^2),n)*m,n);
        elseif(qm(xz)=='0')
            c=(mod(c^2,n));
        end
        xz=xz+1;
    end
    c1(o)=c;
	o = o+1;     % <----------------- here (remove the break)
end
o=1;
fprintf('\nThe encrypted message is \n');
while(o<=over)
    fprintf('\t%d',c1(o));
    o=o+1;
end
fprintf('\n')    % <-------------------- here (add this)