NAME

Math::Libgsl::Permutation - An interface to libgsl, the Gnu Scientific Library - Permutations.

SYNOPSIS

use Math::Libgsl::Raw::Permutation :ALL;

use Math::Libgsl::Permutation;

DESCRIPTION

Math::Libgsl::Permutation provides an interface to the permutation functions of libgsl, the GNU Scientific Library.

This package provides both the low-level interface to the C library (Raw) and a more comfortable interface layer for the Raku programmer.

new(:$elems!)

new($elems!)

The constructor accepts one parameter: the number of elements in the permutation; it can be passed as a Pair or as a single value. The permutation object is already initialized to the identity (0, 1, 2 … $elems - 1).

init()

This method initialize the permutation object to the identity and returns self.

copy($src! where * ~~ Math::Libgsl::Permutation)

This method copies the permutation $src into the current permutation object and returns self.

get(Int $elem! --> Int)

This method returns the permutation value at position $elem.

all(--> Seq)

This method returns a Seq of all the elements of the current permutation.

swap(Int elem2!)

This method swamps two elements of the current permutation object and returns self.

size(--> Int)

This method returns the size of the current permutation object.

is-valid(--> Bool)

This method checks whether the current permutation is valid: the n elements should contain each of the numbers 0 to n - 1 once and only once.

reverse()

This method reverses the order of the elements of the current permutation object.

inverse($dst! where * ~~ Math::Libgsl::Permutation)

This method computes the inverse of the current permutation and stores the result into $dst.

next()

prev()

These functions advance or step backwards the permutation and return self, useful for method chaining.

bnext(--> Bool)

bprev(--> Bool)

These functions advance or step backwards the permutation and return a Bool: True if successful or False if there's no more permutation to produce.

permute(@data!, Int $stride! --> List)

This method applies the current permutation to the @data array with stride $stride.

permute-inverse(@data!, Int $stride! --> List)

This method applies the inverse of the current permutation to the @data array with stride $stride.

permute-complex64(Complex @data!, Int $stride! --> List)

This method applies the current permutation to the @data array array of Complex with stride $stride.

permute-complex64-inverse(Complex @data!, Int $stride! --> List)

This method applies the inverse of the current permutation to the @data array of Complex with stride $stride.

permute-complex32(Complex @data!, Int $stride! --> List)

This method applies the current permutation to the @data array array of Complex with stride $stride, trating the numbers as single precision floats.

permute-complex32-inverse(Complex @data!, Int $stride! --> List)

This method applies the inverse of the current permutation to the @data array of Complex with stride $stride, trating the numbers as single precision floats.

permute-vector(Math::Libgsl::Vector $v)

This method applies the permutation to a Vector object and returns the Vector object itself. As in the case of the Vector object, this method is available for all the supported data type, so we have

• permute-vector-num32

• permute-vector-int32

• permute-vector-uint32

…and so on.

permute-vector-inv(Math::Libgsl::Vector $v)

This method applies the inverse permutation to a Vector object and returns the Vector object itself. As in the case of the Vector object, this method is available for all the supported data type, so we have

• permute-vector-inv-num32

• permute-vector-inv-int32

• permute-vector-inv-uint32

…and so on.

permute-matrix(Math::Libgsl::Matrix $m) This method applies the permutation to a Matrix object and returns the Matrix object itself. As in the case of the Matrix object, this method is available for all the supported data type, so we have

• permute-matrix-num32

• permute-matrix-int32

• permute-matrix-uint32

…and so on.

write(Str $filename! --> Int)

This method writes the permutation data to a file.

read(Str $filename! --> Int)

This method reads the permutation data from a file. The permutation must be of the same size of the one to be read.

fprintf(Str format! --> Int)

This method writes the permutation data to a file, using the format specifier.

fscanf(Str $filename!)

This method reads the permutation data from a file. The permutation must be of the same size of the one to be read.

multiply(p2! where _ ~~ Math::Libgsl::Permutation)

This method combines the current permutation with the permutation dst and returns self.

to-canonical($dst! where * ~~ Math::Libgsl::Permutation)

This method computes the canonical form of the current permutation, stores the result into $dst and returns self.

to-linear($dst! where * ~~ Math::Libgsl::Permutation)

This method computes the linear form of the current permutation, stores the result into $dst and returns self.

inversions(--> Int)

This method counts the number of inversions in the current permutation.

linear-cycles(--> Int)

This method counts the number of cycles in the current permutation given in linear form.

canonical-cycles(--> Int)

This method counts the number of cycles in the current permutation given in canonical form.

C Library Documentation

For more details on libgsl see https://www.gnu.org/software/gsl/. The excellent C Library manual is available here https://www.gnu.org/software/gsl/doc/html/index.html, or here https://www.gnu.org/software/gsl/doc/latex/gsl-ref.pdf in PDF format.

Prerequisites

This module requires the libgsl library to be installed. Please follow the instructions below based on your platform:

Debian Linux and Ubuntu 20.04+

sudo apt install libgsl23 libgsl-dev libgslcblas0

That command will install libgslcblas0 as well, since it's used by the GSL.

Ubuntu 18.04

libgsl23 and libgslcblas0 have a missing symbol on Ubuntu 18.04. I solved the issue installing the Debian Buster version of those three libraries:

• http://http.us.debian.org/debian/pool/main/g/gsl/libgslcblas0_2.5+dfsg-6_amd64.deb

• http://http.us.debian.org/debian/pool/main/g/gsl/libgsl23_2.5+dfsg-6_amd64.deb

• http://http.us.debian.org/debian/pool/main/g/gsl/libgsl-dev_2.5+dfsg-6_amd64.deb

Installation

To install it using zef (a module management tool):

$ zef install Math::Libgsl::Permutation

AUTHOR

Fernando Santagata [email protected]

COPYRIGHT AND LICENSE

Copyright 2020 Fernando Santagata

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.