Find each element that is less than some element to its right

Question

I need to find elements of a vector that are less than one of more elements that come after it. It\'s easy to do in a loop:

x = some_vector_values;
for m = 1         


        

Answer 1

If you would like to find elements that are less than some element to its right, you can do this also:

x = some_values'; % x should be a column vector to use this
h = hankel(x);
m = max(h,[],2);
f = find(x

The hankel matrix will show the elements to the right as it goes down the rows.

Then you can use the indices or true/false to iterate through a for loop and perform some operations. Here is an example:

x =

     9
     8
    16
    16
     4
    10
     9
    13
    15
     1

>> h = hankel(x)

h =

     9     8    16    16     4    10     9    13    15     1
     8    16    16     4    10     9    13    15     1     0
    16    16     4    10     9    13    15     1     0     0
    16     4    10     9    13    15     1     0     0     0
     4    10     9    13    15     1     0     0     0     0
    10     9    13    15     1     0     0     0     0     0
     9    13    15     1     0     0     0     0     0     0
    13    15     1     0     0     0     0     0     0     0
    15     1     0     0     0     0     0     0     0     0
     1     0     0     0     0     0     0     0     0     0

>> m = max(h,[],2)

m =

    16
    16
    16
    16
    15
    15
    15
    15
    15
     1

>> f = find(a