View source for Macaulay2

{{Short description|Computer algebra system}}
{{Infobox software
| name                   = Macaulay2
| title                  = Macaulay2
| logo                   = Macaulay2 9planets logo.jpg
| logo caption           = 
| logo_size              = 
| logo_alt               = 
| screenshot             = <!-- Image name is enough -->
| caption                = 
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| collapsible            = 
| author                 = Daniel Grayson, [[Michael Stillman]]
| developer              = Daniel Grayson, [[Michael Stillman]], [[David Eisenbud]]
| released               = 1993 <!-- {{Start date and age|YYYY|MM|DD|df=yes/no}} -->
| discontinued           = 
| latest release version = 1.24.11
| latest release date    = {{Start date and age|2024|11}}
| latest preview version = 
| latest preview date    = <!-- {{Start date and age|YYYY|MM|DD|df=yes/no}} -->
| programming language   = [[C++]] and [[C (programming language)|C]]
| operating system       = 
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| size                   = 
| language               = 
| language count         = <!-- DO NOT include this parameter unless you know what it does -->
| language footnote      = 
| genre                  = [[Computer algebra system]]
| license                = [[GNU General Public License]], version 2 or 3
| website                = {{URL|https://macaulay2.com/}}
}}

'''Macaulay2''' is a [[Free software|free]] [[computer algebra system]] created by Daniel Grayson (from the [[University of Illinois at Urbana–Champaign]]) and [[Michael Stillman]] (from [[Cornell University]]) for computation in [[commutative algebra]] and [[algebraic geometry]].

==Overview==
Macaulay2 is built around fast implementations of algorithms useful for computation in commutative algebra and algebraic geometry.  This core functionality includes arithmetic on rings, modules, and matrices, as well as algorithms for [[Gröbner bases]], [[free resolution]]s, [[Hilbert series]], [[determinants]] and [[Pfaffians]], [[factorization|factoring]], and similar.  In addition, the system has been extended by a large number of packages.  Nearly 200 packages are included in the distribution of Macaulay2 as of 2019, and notable package authors include [[Craig Huneke]] and [[Frank-Olaf Schreyer]].<ref>{{cite web|url=https://faculty.math.illinois.edu/Macaulay2/Packages/|title=Packages|website=Macaulay2|access-date=October 13, 2019}}</ref>  The [[Journal of Software for Algebra and Geometry]] has published numerous packages and programs for Macaulay2.<ref>{{cite web|url=https://msp.org/jsag/|title=Journal of Software for Algebra and Geometry|publisher=Mathematical Science Publishers|access-date=October 5, 2019}}</ref>

Macaulay2 has an interactive [[command-line interface]] used from the terminal (see {{Section link||Sample session}}).  It can also use [[emacs]] or [[GNU TeXmacs]] as a user interface.<ref>{{cite web|url=https://faculty.math.illinois.edu/Macaulay2/Screenshots/|title=Screenshots|website=Official Macaulay2 website|access-date=October 4, 2019}}</ref>

Macaulay2 uses its own [[interpreted language|interpreted]] [[high-level programming language]] both from the command line and in saved programs.  This language is intended to be easy to use for mathematicians, and many parts of the system are indeed written in the Macaulay2 language.  The algebraic algorithms that form the core functionality are written in [[C++]] for speed.  The interpreter itself is written in a custom type safety layer over [[C (programming language)|C]].<ref name="mac2book">{{cite book | last1 = Eisenbud | first1 = David | author1-link=David Eisenbud|last2 = Grayson | first2 = Daniel | last3 = Stillman | first3 = Michael | author3-link=Michael Stillman| last4 = Sturmfels | first4 = Bernd | author4-link=Bernd Sturmfels| title = Computations in algebraic geometry with Macaulay 2 | series= Algorithms and Computation in Mathematics|volume= 8|publisher = Springer-Verlag | location = Berlin| year = 2002 | isbn = 3-540-42230-7 | url = https://faculty.math.illinois.edu/Macaulay2/Book/ |mr=1949544|doi=10.1007/978-3-662-04851-1}}</ref>  Both the system and the programming language are published under the [[GNU General Public License]] version 2 or 3.<ref>{{cite web|url=https://github.com/Macaulay2/M2/blob/master/M2/Macaulay2/COPYING-GPL-2|title=Macaulay2 COPYING-GPL-2 license|website=Macaulay2 github site}}</ref>

==History==
Stillman, along with [[Dave Bayer]] had authored the predecessor system, '''Macaulay''', beginning in 1983.  They named Macaulay after [[Francis Sowerby Macaulay]], an English mathematician who made significant contributions to [[algebraic geometry]].  The Macaulay system showed that it was possible to solve actual problems in algebraic geometry using Gröbner basis techniques, but by the early 1990s, limitations in its architecture were becoming an obstruction.  Using the experience with Macaulay, Grayson and Stillman began work on Macaulay2 in 1993.  The Macaulay2 language and design has a number of improvements over that of Macaulay, allowing for infinite coefficient rings, new data types, and other useful features.<ref name="mac2book"/>

Macaulay continued to be updated and used for some time after the 1993 introduction of Macaulay2.  The last released version was 3.1, from August 2000.  The Macaulay webpage currently recommends switching to Macaulay2.<ref>{{cite web|url=http://www.math.columbia.edu/~bayer/Macaulay/|title=Official Macaulay website|access-date=October 4, 2019}}</ref>

Macaulay2 has been updated regularly since its introduction.<ref>{{cite web|url=https://faculty.math.illinois.edu/Macaulay2/doc/Macaulay2-1.21/share/doc/Macaulay2/Macaulay2Doc/html/_changes_spto_sp__Macaulay2_cm_spby_spversion.html|title=Changes by Version|website=Macaulay2 Documention|access-date=July 7, 2023}}</ref>  [[David Eisenbud]] has been listed as a collaborator on the project since 2007.<ref>{{cite web|url=https://faculty.math.illinois.edu/Macaulay2/doc/Macaulay2/share/doc/Macaulay2/Macaulay2Doc/html/___The_spauthors.html|title=The Authors|website=Macaulay2 Documentation|access-date=October 5, 2019}}</ref>

==Sample session==
The following session defines a [[polynomial ring]] {{mvar|S}}, an ideal {{mvar|I}} inside {{mvar|S}}, and the [[quotient ring]] <math>R = S/I</math>.  The text <code>i1 :</code> is the 1st input prompt in a session, while <code>o1</code> is the corresponding output.
<syntaxhighlight lang="macaulay2">
i1 : S=QQ[a,b,c,d,e]

o1 = S

o1 : PolynomialRing

i2 : I=ideal(a^3-b^3, a+b+c+d+e)

             3    3
o2 = ideal (a  - b , a + b + c + d + e)

o2 : Ideal of S

i3 : R = S/I

o3 = R

o3 : QuotientRing
</syntaxhighlight>

==Reception==
In a 2006 interview, [[Andrei Okounkov]] cited Macaulay2 along with [[TeX]] as a successful [[open-source software|open-source]] project used in [[mathematics]] and suggested that funding agencies look into and learn from these examples.<ref>Muñoz, Vicente; Persson, Ulf (2006), [http://www.ems-ph.org/journals/newsletter/pdf/2006-12-62.pdf "Interviews with three Fields medallists"], ''[[European Mathematical Society]] Newsletter'' (62):32-36</ref>  Macaulay2 has been cited in over 2,600 scholarly publications.<ref>{{cite web|url=https://faculty.math.illinois.edu/Macaulay2/Publications/#papers|title=Some papers that refer to Macaulay2|website=Macaulay2 Documention|access-date=February 11, 2022}}</ref><ref>{{cite web|url=https://scholar.google.com/scholar?cluster=5544339878767751576|title=Macaulay2 citations|website=Google Scholar|access-date=February 11, 2022}}</ref>

==See also==
{{Portal|Free and open-source software}}
* [[Singular (software)|Singular]] and [[CoCoA]], two other computer algebra systems that are specialized for computation in commutative algebra
* [[Comparison of computer algebra systems]]

==References==
{{Reflist}}

==Further reading==
* {{cite book | last1 = Eisenbud | first1 = David | author1-link=David Eisenbud|last2 = Grayson | first2 = Daniel | last3 = Stillman | first3 = Michael | author3-link=Michael Stillman| last4 = Sturmfels | first4 = Bernd | author4-link=Bernd Sturmfels| title = Computations in algebraic geometry with Macaulay 2 | series= Algorithms and Computation in Mathematics|volume= 8|publisher = Springer-Verlag | location = Berlin| year = 2002 | isbn = 3-540-42230-7 | url = https://faculty.math.illinois.edu/Macaulay2/Book/ |mr=1949544|doi=10.1007/978-3-662-04851-1}}  (Full text available online.)
* {{cite book | last=Schenck | first=Hal |author-link=Hal Schenck | title=Computational Algebraic Geometry | publisher=Cambridge University Press | location=Cambridge, UK | year=2003 | isbn=978-0-511-75632-0 | series=London Mathematical Society Student Texts | volume=58 | doi=10.1017/cbo9780511756320 |mr=2011360}}

==External links==
*{{Official website|https://faculty.math.illinois.edu/Macaulay2/}} for Macaulay2 <!-- say for Macaulay2 to distinguish from Macaulay predecessor -->
*[https://www.unimelb-macaulay2.cloud.edu.au/ Web interface] to Macaulay2

{{Computer algebra systems}}

[[Category:Computer algebra system software for Linux]]
[[Category:Domain-specific programming languages]]
[[Category:Free computer algebra systems]]