Getting incorrect indices with Max function

Hi, I'm scanning through a matrix and getting the maximum values in a odd interval (you'll see in my code) However my problem is that the indicies that I am getting are incorrect and strange, going backwards when the indicies should be going forwards.

   b=1;
 for i=1:2274876
    if(mod(i,2)==0)
        continue
    end
     [T(b),M(b)]=max(Y1(1+(i-1)*58:59+(i-1)*58));
     b=b+1;
 end

In my code Y1 is the matrix that I am scanning through and T is supposed to store the max points in that interval while M is supposed to give the indices corresponding. I was then going to take the indices and create another matrix that has all the X coordinate points relating to that indicy. Here's just the first 15 or so slots of M that I am receiving. As you can see from my code the interval shouldn't even have these values by the second iteration. Meaning that at the minimum my indicy should have went up by 59 at the next iteration.

1 46 33 24 20 53 48 41 58 5 3 23 8 23 28

Can anyone can point out what I'm doing wrong?

[Roger Stafford]

Also your intervals are overlapping. They go:

1:59, 59:117, 117:175, etc.

so 59, 117, etc each lie in two intervals.

[Swapneal Jain]

I see, thank you. I wouldn't have noticed that

Answer 1

[Star Strider]

The indices it returns are relative to the position of the maximum value in the argument vector, not the absolute index.

Example —

v = rand(1, 15);
v(7) = 1;
[M(1),P(1)] = max(v);
[M(2),P(2)] = max(v(5:10));
Result = [M; P]

Result =
     1     1
     7     3

So you need to correct for the offsets in your argument vector ranges to get the absolute index values.

[Swapneal Jain]

That makes things much clearer, thank you

[Star Strider]

My pleasure.