really need help on this question!!!! I want to calculate the sum of all odd number, where do I do wrong?

clear all, close all, clc, format compact, format long g

A=[12 2 33 15 66;
    40 54 79 14 14;
    88 2 54 30 47;
    37 85 92 14 48;
    55 19 88 62 37;
    33 12 23 17 25;
    75 59 40 26 24;
    9 20 44 85 88;
    45 57 36 25 49;
    92 62 46 88 58];

answer=0;
for m=1:length(A);
    for n=1:length(A); 
        if rem(A(m,n),1)==0
            answer=answer+A(m,n);
        end 
    end
end
answer

[Roger Stafford]

The trouble with your method lies in the use of ‘length(A)’. By definition this is the maximum of the dimension sizes of the array A, which in your case would be 10 which is the number of rows - that is, the size of the first dimension. Accordingly, where you write “for n=1:length(A)” your code tries to reference column numbers, n, in A(m,n) which are greater than 5, and A has no such columns. For that reason Matlab will complain with an appropriate error message.

What you should have written is this:

   for m=1:size(A,1);
     for n=1:size(A,2);
       .....A(m,n)....

This will match the true sizes of A along its two dimensions.

[kanghao he]

I have tried what you are saying. Really appreciated. Unfortunately, the correct value should be 909 instead of 2225.

[James Tursa]

Change your test from

        if rem(A(m,n),1)==0

to

        if rem(A(m,n),2)==1

Answer 1

[Andrei Bobrov]

A=[12 2 33 15 66;
      40 54 79 14 14;
      88 2 54 30 47;
      37 85 92 14 48;
      55 19 88 62 37;
      33 12 23 17 25;
      75 59 40 26 24;
      9 20 44 85 88;
      45 57 36 25 49;
      92 62 46 88 58];

out = sum(A(rem(A,2)~=0));

[kanghao he]

Thank you. It's correct, but may I ask how you came up this?