Finding the maximum of a vector using only for loop and the routine length

Dear all,

I have been struggling with the programming of this script. I am trying to find the maximum number of a row vector, using only the routine length. So I have written the following script :

clear all, clc

v = [ 1 5 6 23 43 5 2 5 2 23 53 45 6 3 4] ;

number = 0 ;

max_number = 0 ;

for k = 1: length(v) -2

if v(k+1) > v(k) && v(k+1) > v(k+2)

number = v(k+1) ;

elseif v(k) > v(k+1) && v(k) > v(k+2)

number = v(k) ;

elseif v(k+2) > v(k+1) && v(k+2) > v(k)

number = v(k+2) ;

end

number

end

my problem is that matlab is taking comparing every 3 elements with each other... what can I do about it?

thanls alot

[Walter Roberson]

The problem cannot be solved using only the routine length(). In MATLAB, comparing two numbers is a function call, and it is not possible to sort two numbers without comparing them.

Answer 1

[KSSV]

v = [ 1 5 6 23 43 5 2 5 2 23 53 45 6 3 4] ; 

n = length(v) ;
themax = 0 ;
pos = 1 ; 
for i = 1:n
  if v(i)> themax 
    themax = v(i) ; 
    pos = i ; 
  end
end
% check
[val,idx] = max(v) 
[themax, pos]

[Mostafa Yaghi]

Thank you very much,

could you please explain to me what is the problem with my code, I understand ur code. But what is the difference that is making matlab taking every 3 elements with each other, instead of the whole vector ?

[KSSV]

You need not to compare two elements ..you can compare one by one each element to make things easy and to avoid confusion.

[Mostafa Yaghi]

thanks alot

[KSSV]

Thank sis accepting/ voting the answer.