# NAME

Math::GSL::Sort - Functions for sorting data

# SYNOPSIS

```
use Math::GSL::Sort qw/:all/;
my $x = [ 2**15, 1.67, 20e5, -17, 6900, 1/3 , 42e-10 ];
my $sorted = gsl_sort($x, 1, $#$x+1 );
my $numbers = [ map { rand(100) } (1..100) ];
my ($status, $smallest10) = gsl_sort_smallest($array, 10, $x, 1, $#$x+1);
```

# DESCRIPTION

gsl_sort_vector($v)

This function sorts the elements of the vector $v into ascending numerical order.

gsl_sort_vector_index($p, $v)

This function indirectly sorts the elements of the vector $v into ascending order, storing the resulting permutation in $p. The elements of $p give the index of the vector element which would have been stored in that position if the vector had been sorted in place. The first element of $p gives the index of the least element in $v, and the last element of $p gives the index of the greatest element in $v. The vector $v is not changed.

gsl_sort_vector_smallest($array, $k, $vector)

This function outputs 0 if the operation succeeded, 1 otherwise and then the $k smallest elements of the vector $v. $k must be less than or equal to the length of the vector $v.

gsl_sort_vector_smallest_index($p, $k, $v)

This function outputs 0 if the operation succeeded, 1 otherwise and then the indices of the $k smallest elements of the vector $v. $p must be a prealocated array reference. This should be removed in further versions. $k must be less than or equal to the length of the vector $v.

gsl_sort_vector_largest($array, $k, $vector)

This function outputs 0 if the operation succeeded, 1 otherwise and then the $k largest elements of the vector $v. $k must be less than or equal to the length of the vector $v.

gsl_sort_vector_largest_index($p, $k, $v)

This function outputs 0 if the operation succeeded, 1 otherwise and then the indices of the $k largest elements of the vector $v. $p must be a prealocated array reference. This should be removed in further versions. $k must be less than or equal to the length of the vector $v.

gsl_sort($data, $stride, $n)

This function returns an array reference to the sorted $n elements of the array $data with stride $stride into ascending numerical order.

gsl_sort_index($p, $data, $stride, $n)

This function indirectly sorts the $n elements of the array $data with stride $stride into ascending order, outputting the permutation in the foram of an array. $p must be a prealocated array reference. This should be removed in further versions. The array $data is not changed.

gsl_sort_smallest($array, $k, $data, $stride, $n)

This function outputs 0 if the operation succeeded, 1 otherwise and then the $k smallest elements of the array $data, of size $n and stride $stride, in ascending numerical. The size $k of the subset must be less than or equal to $n. The data $src is not modified by this operation. $array must be a prealocated array reference. This should be removed in further versions.

gsl_sort_smallest_index($p, $k, $src, $stride, $n)

This function outputs 0 if the operation succeeded, 1 otherwise and then the indices of the $k smallest elements of the array $src, of size $n and stride $stride. The indices are chosen so that the corresponding data is in ascending numerical order. $k must be less than or equal to $n. The data $src is not modified by this operation. $p must be a prealocated array reference. This should be removed in further versions.

gsl_sort_largest($array, $k, $data, $stride, $n)

This function outputs 0 if the operation succeeded, 1 otherwise and then the $k largest elements of the array $data, of size $n and stride $stride, in ascending numerical. The size $k of the subset must be less than or equal to $n. The data $src is not modified by this operation. $array must be a prealocated array reference. This should be removed in further versions.

gsl_sort_largest_index($p, $k, $src, $stride, $n)

This function outputs 0 if the operation succeeded, 1 otherwise and then the indices of the $k largest elements of the array $src, of size $n and stride $stride. The indices are chosen so that the corresponding data is in ascending numerical order. $k must be less than or equal to $n. The data $src is not modified by this operation. $p must be a prealocated array reference. This should be removed in further versions.

` Here is a complete list of all tags for this module :`

- all
- plain
- vector

For more informations on the functions, we refer you to the GSL offcial documentation: http://www.gnu.org/software/gsl/manual/html_node/

# PERFORMANCE

In the source code of Math::GSL, the file "examples/benchmark/sort" compares the performance of gsl_sort() to Perl's builtin sort() function. Its first argument is the number of iterations and the second is the size of the array of numbers to sort. For example, to see a benchmark of 1000 iterations for arrays of size 50000 you would type

` ./examples/benchmark/sort 1000 50000`

Initial benchmarks indicate just slightly above a 2x performance increase over sort() for arrays of between 5000 and 50000 elements. This may mostly be due to the fact that gsl_sort() takes and returns a reference while sort() takes and returns a plain list.

# AUTHORS

Jonathan "Duke" Leto <jonathan@leto.net> and Thierry Moisan <thierry.moisan@gmail.com>

# COPYRIGHT AND LICENSE

Copyright (C) 2008-2020 Jonathan "Duke" Leto and Thierry Moisan

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.