foor loop that outpus a vector question

If i have a 4*4 matrix for example. Using for loop, how can i create a function that returns the index (row number which is coloum 1 of the matrix) of the data which specfically is <60 for the 2nd coloum, <20 for the 3rd coloumn and <50 for the 4th coloum.

how would for loop be used in this situation. help would be awesome.

Answer 1

[Mehmed Saad]

x = [1 2 3 4; 70 62 45 65; 23 17 19 20; 51 34 56 72];
cond = [60 20 50];
ind = avada(x,cond)

 

1. Initialize false array which is off size [3 4]
2. Run for loop for 3 iterations
3. compare 2nd row with condition [70 62 45 65]>=60, then output will be [1 1 0 1]
4. compare 3rd row with condition [23 17 19 20]>=20, then output will be [1 0 0 1]
5. compare 4rth row with condition [51 34 56 72]>=50, then output will be [1 0 1 1]
6. You have all these values in array y i.e = [1 1 0 1;1 0 0 1; 1 0 1 1];
7. sum column wise output will [3 1 1 3]
8. values equal to 3, output will be [1 0 0 1]
9. feed it to x's first row i.e. x(1,[true false false true])

function ind = avada(x,cond)
y = false(size(x)-[1 0]); %iNITIALIZE Y
for i=1:size(x,2)-1 % Run for loop for 3 times i.e. 1 less than 4
 y(i,:) = x(i+1,:)>=cond(i);% condition,all values greater than equal to cond will be true
end
ind = x(1,sum(y)== (size(x,2)-1)); %
end

[Aroi Mehu]

thank you for explaining that.