lines 9-69 of file: include/cppad/utility/index_sort.hpp

{xrst_begin index_sort}

Returns Indices that Sort a Vector
##################################

Syntax
******

   # ``include <cppad/utility/index_sort.hpp>``

``index_sort`` ( *keys* , *ind* )

keys
****
The argument *keys* has prototype

   ``const`` *KeyVector* & *keys*

where *KeyVector* is
a :ref:`SimpleVector-name` class with elements that support the ``<``
operation.

ind
***
The argument *ind* has prototype

   *SizeVector* & *ind*

where *SizeVector* is
a :ref:`SimpleVector-name` class with elements of type *Size_t* ,
where *Size_t* is an integral type.
The routine :ref:`CheckSimpleVector-name` will generate an error message
if this is not the case.

Input
=====
The size of *ind* must be the same as the size of *keys*
and the value of its input elements does not matter.

Return
======
Upon return, *ind* is a permutation of the set of indices
that yields increasing order for *keys* .
In other words, for all *i* != *j* ,

   *ind* [ *i* ] != *ind* [ *j* ]

and for *i* = 0 , ... , *size* ``-2`` ,

   ( *keys* [ *ind* [ *i* +1] ] < *keys* [ *ind* [ *i* ] ] ) == ``false``

Example
*******
{xrst_toc_hidden
   example/utility/index_sort.cpp
}
The file :ref:`index_sort.cpp-name` contains an example
and test of this routine.
It return true if it succeeds and false otherwise.

{xrst_end index_sort}