Sort Matrix Elements with Positions

A function to sort values of the matrix elements, providing their positions in original matrix.

Description

SORTMATRIXELEMENTS(A) returns a matrix that is composed of 3 columns:
  first column is the array of the sorted (ascending) values of the
  original matrix second column is the array of corresponding row positions
  and third column is that of column positions.
  
  SORTMATRIXELEMENTS(A,dir) returns sorted values with a descending order
  if dir is equal to -1, or with an ascending order, otherwise.
 
  A : the matrix to be sorted
  dir: direction of the sort, -1 for descending, 1 for ascending (default)
 
  I want to sort the matrix elements and at the same time
  to know the position of each. I will create an array of arrays which
  consists of elements that each has its value, row position and column
  position. An example:
  A = [8 2 6 11; 4 7 9 12; 5 1 3 10];
  Array of arrays (X)
X is [8 1 1;
      2 1 2;
      6 1 3;
     11 1 4;
      4 2 1;
      7 2 2;
      9 2 3;
     12 2 4;
      5 3 1;
      1 3 2;
      3 3 3;
     10 3 4]
And result of the sort (y)
Y is [1 3 2;
      2 1 2;
      3 3 3;
      4 2 1;
      5 3 1;
      6 1 3;
      7 2 2;
      8 1 1;
      9 2 3;
     10 3 4;
     11 1 4;
     12 2 4 ]

• MATLAB release: MATLAB 7.1.0 (R14SP3)

[Matt Fig]

There is no help, and no real H1 line in this file. Why not use the faster engine:

[As,Y] = sort(A(:));
[Y,c] = ind2sub(size(A),Y);
Y = [As,Y,c];

[Kadir]

thanks for the comment! i'm not at good using the built-in functions. but you're right. i will use your code and add help.

[Gianni Schena]

matlab sort is much faster! ,
one may consider improving the original matlab sort by adding an additional parameter (say k) for ordering at most the first kth largest elements and the first k corresponfing indices

[Dinesh Jayaraman]

I know it's simple and all, but shouldn't matlab be providing a straight function for something as basic as this? anyway thanks, Matt.
I spent an hour trying to do this very thing, 'cos i didn't know about ind2sub() and then on a hunch, checked here!

[Shyamsunder]

I am converting an image into a matrix using imread. Then I am taking the R component. After that I am sorting the matrix elements using your program. Here the problem is that for the rows and columns greater than the value 255, the indices are not getting the value i.e. there's no indices such as (300,400) for a value. likewise no index like this one:(400,500) etc.

But if I take ones(512,512). The indices are shown for more than 255.

Please give a solution to this problem.