lex_sort
========

lexicographic matrix rows sorting



Calling Sequence
~~~~~~~~~~~~~~~~


::

    [N, [k]]=lex_sort(M [,sel] [,'unique'])




Arguments
~~~~~~~~~

:M real matrix
: :N real matrix
: :k column vector of integers
:



Description
~~~~~~~~~~~

the `lex_sort` function is now obsolete. It can be replaced by
functions `gsort`_ and `unique`_.

`N=lex_sort(M)` sorts the rows (as a group) of the matrix `M` in
ascending order. If required the output argument `k` contains the
ordering: `[N,k]=lex_sort(M)` returns `k` such as `N` is uequal to
`M(k,:)` .

`N=lex_sort(M,sel [,'unique'])` produces the same result as the
following sequence of instructions:


::

    [N,k]=lex_sort(M(:,sel) [,'unique']);
    N=M(k,:)


The `'unique'` flag has to be given if one wants to retain only unique
rows in the result. Note that `lex_sort(M,sel,'unique')` retains only
rows such that M(:,sel) are unique.



Examples
~~~~~~~~


::

    M=`round`_(2*`rand`_(20,3));
    
    lex_sort(M)
    lex_sort(M,'unique')
    [N,k]=lex_sort(M,[1 3],'unique')




See Also
~~~~~~~~


+ `gsort`_ sorting by quick sort agorithm
+ `unique`_ extract unique components of a vector or matrices


.. _gsort: gsort.html
.. _unique: unique.html