# 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>