Math::...ultiset(3pm)

💅 NAME 💅

Math::GSL::Multiset — literally just multisets manipulation bestie, that's the whole vibe. It's part of the user contributed Perl documentation, so you know it's the good stuff. ✨

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🌸 SYNOPSIS 🌸

okay so first you gotta pull it in:

use Math::GSL::Multiset qw/:all/;

my $ms = Math::GSL::Multiset->($n, $k);

my $value = $ms->get(2);

# compute next multiset
$ms->next;
# compute the previous multiset

# clone a multiset
my $other = $ms->clone();

yes she's giving main character energy with the constructor, the get, the next, and the clone. slay. 🫶

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🦋 DESCRIPTION 🦋

okay so picture this: a multiset c is represented by an array of k integers, and every single one of them lives in the range 0 to n-1. and here's the twist — each value c_i can show up more than once. not me being obsessed with repetition 💀.

so what does that actually mean? the multiset c corresponds to the indices of k elements chosen from an n element vector with replacement. that's the math tea. and in mathematical terms: n is the cardinality of the multiset, while k is the maximum multiplicity of any value. periodt. 👑

🎀 Object Oriented API 🎀

Handy Perl-style OO API for Multisets. so convenient, so cute, so iconic.

• new — Creates a new multiset with parameters n, k and initializes it to the lexicographically first multiset element, i.e., 0 repeated k times. firsties!! 🥇

my $ms = Math::GSL::Multiset->($n, $k);

• init_first — Initializes the multiset to the lexicographically first multiset element, i.e. 0 repeated k times. back to the beginning, no cap.

$ms->init_first;

• init_last — Initializes the multiset c to the lexicographically last multiset element, i.e. n-1 repeated k times. she went to the end bestie 🏁

$ms->init_last;

• get — Returns the value of the i-th element of the multiset. but listen — if i lies outside the allowed range of 0 to k-1 then the error handler is invoked and 0 is returned. so stay in your lane fr fr 😭

my $val = $ms->get($k-1);

• next — Advances the multiset to the next multiset element in lexicographic order and returns GSL_SUCCESS. but if no further multisets elements are available it returns GSL_FAILURE and leaves the multiset unmodified (no touchy 🙈). Starting with the first multiset and repeatedly applying this function will iterate through all possible multisets of a given order. it's giving completionist energy.

$ms->next();

• prev — Steps backwards from the multiset to the previous multiset element in lexicographic order, returning GSL_SUCCESS. If no previous multiset is available it returns GSL_FAILURE and leaves the multiset unmodified. so she can walk backwards too, versatile queen 👑

$ms->prev();

• to_list — Creates a Perl list of integers with the values from the multiset, starting at index 0 and ending at index $k-1. here's your lil list bestie:

@data = $ms->to_list;

• clone — Creates a new multiset with the same size, and same values. twin where have you been 💖

my $new = $ms->clone;

🧚 GSL API 🧚

For reference on these methds, please consult the GSL documentation. (that's your homework bestie, go read it 📚)

• gsl_multiset_calloc
• gsl_multiset_alloc
• gsl_multiset_init_first
• gsl_multiset_init_last
• gsl_multiset_free
• gsl_multiset_memcpy
• gsl_multiset_get
• gsl_multiset_n
• gsl_multiset_k
• gsl_multiset_data
• gsl_multiset_valid
• gsl_multiset_next
• gsl_multiset_prev
• gsl_multiset_fwrite
• gsl_multiset_fread
• gsl_multiset_fprintf
• gsl_multiset_fscanf

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🌈 AUTHORS 🌈

Jonathan "Duke" Leto <jonathan@leto.net> and Thierry Moisan <thierry.moisan@gmail.com> — absolute legends, we stan 🫶

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⭐ COPYRIGHT AND LICENSE ⭐

Copyright (C) 2008-2024 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.

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okay that's the whole page bestie, you ate it up 💅

this iconic lil page is from the User Contributed Perl Documentation, running alongside perl v5.42.3, dated 2026-08-20 — and the manual name is Math::GSL::Multiset(3pm). mwah, bye 🎀✨