Monthly Downloads: 213
Programming language: Erlang
License: BSD 2-clause "Simplified" License
Latest version: v0.13.3

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sfmt-erlang: SIMD-oriented Fast Mersenne Twister (SFMT) for Erlang

This software is no longer maintained

CAUTION: this software is no longer maintained. Migrate to the default rand module for OTP 18 and later because they are well-supported and use faster and better algorithms.

Version and credit information

  • Version 0.14.0 15-MAY-2021
  • Edited and written by Kenji Rikitake (Kenji Rikitake Professional Engineer's Office)
  • Email contact: [email protected]

Build and test commands

  • Building: rebar3 compile
  • C NIF Documentation: doxygen (requires Doxygen 1.9.1 or later)
  • Erlang Documentation: rebar3 edoc
  • Testing: rebar3 ct
  • Execution speed benchmark: execute rebar3 shell and run sfmt_tests:test_speed() and sfmt_pure_tests:test_speed()
  • Cleaning up: rebar3 clean

Use rebar3 to build since 0.14.0

  • Since 14.0, erlang.mk and mix.exs are removed. Use rebar3 to build.

Use 0.13.2 and later for OTP 23

  • erlang.mk is updated to stop using -lerl_interface. This is required for a successful build in OTP 23.

Security notice regarding the PHP mt_seed() vulnerability

Ambionics Security published an internal state retrieval algorithm of PHP mt_rand() on 6-JAN-2020. sfmt-erlang uses the same seed-to-internal-state initialization algorithm at the function init_gen_rand/1.

For reducting the possibility of the internal state revelation, use init_by_list32/1 instead, better combined with rand:uniform/1. Raimo Niskanen published a piece of code for this purpose.

Note well that sfmt-erlang has no cryptographic security guarantee and MUST NOT be used for security purposes such as password generation.

Also: Version 0.13.0 and 0.13.1 Erlang and C code files are identical. Users have no need to upgrade.

Thanks to Shiro Kawai for the notification of the seed initialization algorithm issue.


Copyright (c) 2010-2021 Kenji Rikitake and Kyoto University. All rights reserved.

Copyright (c) 2006,2007 Mutsuo Saito, Makoto Matsumoto and Hiroshima University. All rights reserved.

See the file LICENSE for the license (new/simplified BSD license).

Details of SFMT algorithm

This software is based on SFMT ver. 1.3.3 (SIMD oriented Fast Mersenne Twister(SFMT)) by Mutsuo Saito (Hiroshima University) and Makoto Matsumoto (Hiroshima University). See http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index.html for the further details.

Note well: only (219937 - 1) period is supported.

Available modules

  • module sfmt: SFMT with C NIFs
  • module sfmt_pure: SFMT with pure Erlang
  • See CHANGES.md for the detail of miscellaneous changes


  • Compiler requirement: C99 support (modern Clang and gcc will do): <inttypes.h> required
  • See c_src/sfmt_nif.c for the details
  • Also refer to sfmt-extstate at http://github.com/jj1bdx/sfmt-extstate
  • The version number of this NIF is 101 (see NIF_LOAD_INFO macro value)

Tested platforms

  • macOS 10.15.7 with Erlang/OTP 24.0
  • Ubuntu 20.10 with Erlang/OTP 24.0
  • sfmt-erlang will work with older OTP versions

hex.pm support

  • hex is supported through rebar3_hex plugin
  • NIF building errors fixed (0.12.7 and later)
  • Package name: sfmt
  • Note: all builds including C and Erlang source compilation are done with rebar3

API compatible with the rand module

seed/3, uniform/0, uniform/1, uniform_s/1, uniform_s/3 

On HiPE usage

  • HiPE is removed from OTP 24, no longer configured
  • sfmt module is NIFnized so does not coexist with HiPE
  • On the other hand, sfmt_pure module can be compiled with HiPE or +native "+{hipe, [o3]}" erlc compile option, which will result in 40% to 100% speedup on 64-bit machines


  • No more new feature; more load testing needed
  • More documentation
  • Code upgrading/reloading behavior check

Code authors:

  • Kenji Rikitake
  • Mutsuo Saito
  • Makoto Matsumoto
  • Dan Gudmundsson
  • Michael Truog
  • Michael Chmielewski
  • David Whitlock
  • Pierre Fenoll


  • Dave "dizzyd" Smith
  • Tuncer Ayaz
  • Tim Bates (random_mt.erl implementator of Mersenne Twister)
  • Richard O'Keefe
  • Yurii Rashkovskii
  • Kostis Sagonas
  • Michael Gebetsroither
  • Shunichi Shinohara
  • Loïc Hoguin
  • @timCF of GitHub
  • Shiro Kawai


During the compatibility test of this software, Kenji Rikitake used the supercomputer service provided by Academic Center for Computing and Media Studies (ACCMS), Kyoto University.

Erlang Solutions kindly gave Kenji Rikitake an opportunity to give a presentation about this software at Erlang Factory SF Bay 2011.

Pepabo R&D Institute of GMO Pepabo, Inc. kindly gives the financial support for this project.

*Note that all licence references and agreements mentioned in the sfmt README section above are relevant to that project's source code only.