How can I add two vectors of same length or different length using for-loops?

for example: x=[9 9 9 9];y=[9 9 9 9] The result should be as z=[1 9 9 9 8]. How can I write a code using for-loops or any other means. Greatly appreciate help

[KSSV]

How x = [9 9 9 9], y = [9 9 9 9] becomes z = [1 9 9 9 8]? What is the logic?

[Sunil Kunjachan]

I mean direct addition from right to left. That is first 9+9=18. Then that 1 carry over to the next left position. There it 9+9+1=19.Again that 1 is carry over to the next left position and add. The result is 19998. Thanks for the reply

Answer 1

[Jan]

Using the string conversion is efficient as long as the input does not have more than 16 digits. For longer vectors the limited precision of double will crop the least significant digits. For an arbitrary number of digits:

function c = DigitsAdd(a, b)
% Author: Jan Simon, License: Creative Commons Attribution Share Alike 3.0
isrow = size(a, 2) > 1;
na = numel(a);
nb = numel(b);
a  = [zeros(max(1, nb - na + 1), 1); a(:)];  % Pad with at least one zero
b  = [zeros(max(1, na - nb + 1), 1); b(:)];
c  = a + b;  % Standard addition

carry = 0;   % Shift the values above 10
for k = numel(c):-1:1
  cc    = c(k) + carry;
  c(k)  = rem(cc, 10);
  carry = (cc - c(k)) / 10;  % Must be integer
end

if c(1) == 0       % Crop leading zero
  c = c(2:numel(c));
  % If wanted crop all leading zeros:
  % c = c(find(c, 1):numel(c));
end
if isrow % Reply a row vector if input "a" was one
  c = c.';
end

Answer 2

[Sunil Kunjachan]

Thank you very much Jan.