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meankondo

meankondo is a tool to compute the flow equation for fermionic hierarchical models. It was written to solve the hierarchical Kondo model (hence the name), but can be used for a large class of other fermionic hierarchical models as well.

meankondo is written in C, and can run on any POSIX compliant system, including GNU/Linux and OSX. meankondo is linked against the GNU MPFR library.

The main features of meankondo v1.5:

• Compute the flow equation for any renormalizable fermionic hierarchical model exactly, provided a comprehensive list of all running coupling constants is provided.
• Numerical iteration of flow equations using extended precision floats or MPFR floats.
• Various symbolic operations on flow equations.
• Conversion of flow equations to C, javascript and LaTeX.

Changelog

• Version 1.5:
  The update to version 1.5 is rather substantial, and introduces some minor backward-incompatibilities:
  • The header "#!symbols" has been replaced by "#!virtual_fields"
  • Multiplying polynomials using the '*' symbol is no longer supported (or, rather, the symbolic capabilities of meankondo were enhanced, and the syntax has been changed).
  • 'meantools exp' has been removed (its functionality is now handled by other means)
  • 'meantoolds derive' has been replaced by 'meantools differentiate'
  In addition, we have made the following improvements:
  • The symbolic capabilities were enhanced: polynomials can now be multiplied, added, exponentiated, and their logarithms can be taken directly in the configuration file.
  • The flow equation can now be processed after being computed using the various "#!postprocess_*" entries.
  • Deprecated kondo_preprocess.
  • Compute the mean using an LU decomposition if possible.
  • More detailed checks for syntax errors in configuration file.
  • Check that different '#!group' entries are indeed uncorrelated.
  • New flags in meankondo: '-p' and '-A'.
  • New tool: meantools expand.
  • Improve conversion to LaTeX using meantools-convert
  • Assign terms randomly to different threads.
  • Multiple bug fixes
• Version 1.4:
  • Support MPFR floats in numkondo.
  • Remove '-D' option (error tolerance) from numkondo.
• Version 1.3.1:
  • '-C' flag in meantools-derive.
• Version 1.3:
  • Support for non-commuting coefficients.
  • Project files for the s-d model.

Download

meankondo is made available under an Apache 2.0 license, which allows copying, sharing and modifying the source code, among other things. Details can be found at https://www.apache.org/licenses/LICENSE-2.0.

The source code is made available here:

• Source tarball: meankondo-1.5.tar.gz
• Git repository: meankondo-git

In addition, the following distribution-dependent packages are made available:

• Arch linux: PKGBUILD

Documentation

The technical details of how to use meankondo are provided in the man pages provided with the source code. A more conceptual point of view on how meankondo views and manipulates flow equations is available as a monolithic html document:

• meankondo-doc

meankondo_projects

A project is a collection of configuration files and scripts to carry out a particular computation using meankondo. The following projects are available:

• s-d (v1.5-1): hierarchical s-d model (see [G.Gallavotti, I.Jauslin, 2015]) (Documentation)
• graphene (v1.5-1): hierarchical graphene model (see [I.Jauslin, 2022]) (Documentation)
• kondo (v1.3-1): (WARNING: this project is only compatible with meankondo versions 1.2 through 1.4 (not 1.5), available here: meankondo-1.4.tar.gz) hierarchical Kondo model (see [G.Benfatto, G.Gallavotti, I.Jauslin, 2015]) (Documentation)

The version number of a project is of the form meankondo_version-revision where meankondo_version corresponds to the version of meankondo required to read the configuration files and revision indexes the version of the project files themselves, within a meankondo_version. For example, 'v1.3.1-2' means that the configuration files were written for meankondo-1.3.1, and that they are the second revision of these files.

Licensing

As was mentioned earlier, meankondo is licensed under the Apache 2.0 license.

meankondo is linked against the GNU MPFR and GMP libraries, which are licensed under the GNU Lesser General Public License v3.