MATLAB: How to compare an element of array to the rest of the elements

codefunction

I am trying to compare each element of an array with its subsequent elements and get the count of number of times the current element is greater than the subsequent elements.
the following is my code
     function [ z ] = test(i,size_data, num,j,k,sum )
  % test
num=xlsread('MKdata.xlsx');
size_data=size(num);
j=0
k=0
i=1
for (i=i:size_data)
      if num(i) > num([i+1:size_data])
          j=j+1
      else k=k-1
      end
      i=i+1
  end
  sum=j+k
  end
the test data set i am using is
1733  3002  875  164  1464  1399  1039  1096  1812  2347  575  1393  411  283  1407  1294  1102  1886  3058  4587
results shows that every increment of i adds 1 to k and finally i get k=-20, j=0 whereas it should be 26
please guide me, please point out the mistake in logic or syntax

Best Answer

Wouldn't you just do this (vectorized):
% Define some arbitrary random data

data = randi(9, 1, 20)
% Define the element we're going to consider
index = 3;
% Compare each element of an array with its subsequent elements 
% Get logical index that is true when current element is greater.

itIsGreater = data(index) > data(index+1:end)
% Get the count of number of times the current element is greater than the subsequent elements.

theCount = sum(itIsGreater)
You didn't say in words that you want to do that for all possible starting indexes, but if you do, then put it in a loop and make the count depend on starting index.
% Define some arbitrary random data
data = randi(9, 1, 20)
theCount = zeros(1, length(data));
for index = 1 : length(data)
  % Compare each element of an array with its subsequent elements
  % Get logical index that is true when current element is greater.
  itIsGreater = data(index) > data(index+1:end)
  if ~isempty(itIsGreater) % if there is at least 1 greater...
    % Get the count of number of times the current element is greater than the subsequent elements.
    theCount(index) = sum(itIsGreater)
  end
end
% Print to command window..
theCount
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