Project updates: November 2022

Dear FOMCON users, The next update of FOMCON is here with v1.50.4 with one new experimental feature added and several bugs fixed. The main changes are:
  • Feature: Added a way to convert a `fotf` object to a symbolic expression. The new function is `fotf2expr`. Note that this feature requires the **Symbolic Math Toolbox**. There are some updates to existing functions as well. For example, the `poly2str` function now supports a 4th argument which is the kind of multiplication symbol to be inserted according to need — by default, it is empty, i.e. no multiplication symbol is inserted, and this is used in FOMCON GUIs when you see the string expressions for FOTF numerator and denominator.
  • Bugfix: [breaking] FOMCON function `poly2str` being shadowed by a Control System toolbox function of the same name. The solution is to keep this function in FOMCON for backwards-compatibility as an alias to `fpoly2str`. To keep consistency, the function `str2poly` has also been recreated as `str2fpoly`.
  • Bugfix: (regression?) simulating FOTF models with a delay term resulted in an incorrect concatenation of sample vectors (computations were stopped due to an error in the GL solver, so no incorrect results potentially used down the pipeline should have been obtained, i.e., the user would simply see an error message).
As always, if you find any issues with the current release, please send a bugreport via Github.
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Project updates: January 2022

It brings me great pleasure to announce that a new version of FOMCON toolbox (v1.50.1) is finally available! Below, I provide a few details about this release. Major changes:
  • Update to the Grünwald-Letnikov based FODE solver: added higher-order numerical solver options — the default and only available option up to this point was the first order solver; now, the user gets the option of also choosing second and third order numerical schemes for computing the time domain response of systems described by fractional-order transfer function objects. The setting can be configured in the new option `GL_Order` found under `Simulations` in the toolbox configuration.
  • Completely rewritten is the configuration options handler. This is, in some ways, a breaking change, but at the same time one that should not affect the majority of users. Whereas before the user had to store or recall toolbox-wide configuration options him or herself and the configuration was stored in MATLAB workspace rather than in the user’s file system, the new approach is to: (1) Store the configuration as a file in the user’s home directory under the `.fomcon-matlab` folder. This way, the configuration options are persistent from session to session. (2) Perform a check on the options, so if new options are added in the future, there is no backwards compatibility problem. On the other hand, the validity of the inserted values/ranges for the configuration parameters are currently not checked, this is a feature that was also missing previously and will be added in the future.
  • Added a new demo which pertains to the above mentioned solver update to show the differences in the solutions that can be obtained using various methods and with different solver orders.
  • Released a packaged toolbox version of the toolbox.
Minor changes:
  • Some minor bugs/compatibility problems have been fixed.
Known issues:
  • In newer versions of MATLAB, a warning is displayed when the UI of the toolbox configuration dialog is displayed about the deprecation of certain Java components. In FOMCON, a contribution called propertiesGUI is used to display this configuration box and it has not been updated since 2015. In a future version of the toolbox, it is likely to be replaced with a custom, programmatic UI.
What’s more, the toolbox can now be directly installed from MATLAB, so no more GitHub downloads/messing around with MATLAB path. You just locate it in the Add-on Explorer and install it in one click!

And that’s not all!

I would like to direct your attention to an alpha release of FOMCON toolbox for Python 3! You can check it out on GitHub ( and find out more by visiting this link with the information about the associated paper and a conference talk. If you find it useful, please help spreading the word and cite the following paper:

What? There’s even more?

Yes! Many new exciting features in the toolbox are currently being worked on that will be deployed for testing later this year! Stay tuned!
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Project updates: March 2018

The following updates are in effect:
  • The toolbox is now available for download from MathWorks File Exchange. This download always contains the most recent GitHub version. Please leave your comments and ratings, feedback is valuable:
  • The official bug tracker is now also located at GitHub, the old one will be silently closed:
  • The site will stop hosting old toolbox versions and the user will be redirected to MathWorks file exchange upon clicking on “Download” in the menu section. This is done to avoid confusion and also to make the distribution of the toolbox possible from one central source (in this case, GitHub via File Exchange).
  • Due to massive amounts of registration spam, registration could be closed soon. If you have to report a real issue, please use the bug tracker. Otherwise, in case of problems of considerable complexity, please drop me an e-mail. Please understand that due to time limitations I cannot honor simple queries similar to “How do I install the toolbox” or “Feature X doesn’t work, why?”
Taking this opportunity, I would like to thank the community for the support through use of FOMCON toolbox. Active MATLAB developers interested in the field of fractional calculus are welcome to join the development efforts on GitHub!
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Paper Presented at FIE’2017 Conference

A paper entitled “Design of a MATLAB-based Teaching Tool in Introductory Fractional-order Systems and Controls” was presented by Dr. Aleksei Tepljakov at the Frontiers in Education 2017 conference. The slides are available here: or in PDF form.

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Paper to be Presented at TSP’2017 Conference

A paper related to joint efforts of researchers from Tallinn University of Technology, Estonia, and Inonu University, Turkey, in the scope of COST Action CA15225, will be presented by Dr. Aleksei Tepljakov during the special session dedicated to FO systems of the 2017 40th International Conference on Telecommunications and Signal Processing (TSP’2017). The paper is entitled “Multi-Loop Model Reference Adaptive Control of Fractional-Order PID Control Systems”. In this post, you will find a link to supplementary materials for this paper.

Read More »
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Project updates: May 2016


The development of FOMCON toolbox for MATLAB has been moved to GitHub! You can now download the master branch at any time with the latest updates from the fomcon-matlab repository.

This is meant to facilitate the distribution of latest updates and bugfixes. I will still release major versions of the toolbox through this website and maintain the documentation section.

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Project updates: April 2016

UPDATE (April 19, 2016): The impulse() function for FOTF objects has been fixed and the toolbox has been updated to version 1.21b. Download the new version now.

We would like to announce the update of FOMCON toolbox for MATLAB to version 1.2b. Please note that this is a beta release which is intended mostly for evaluation of new features. Previously available features should work as before.

New features
  • Initial support for working with fractional-order state-space models including a Simulink block through the use of FOSS objects. Therefore, fractional-order MIMO systems can now be studied using FOMCON. Because the feature set is preliminary, the release is in “beta” status and previous documentation will not be updated at this time.
Various improvements
  • Started to rewrite some of the basic FOTF support functions (step, impulse, etc.) to make them more compatible with Control System toolbox.
  • Added the possibility to set computation accuracy for internal operations with FOTF objects. It can be set in the FOMCON options structure.
Bug fixes
  • Evaluation of FOTF objects with small coefficients should now work. See the description of the above mentioned improvement. See the associated bug report.

The updated toolbox can be downloaded in the corresponding section.

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Project updates: February 2016

We would like to announce the update of FOMCON toolbox for MATLAB to version 1.1. This release offers several important features mostly related to improvement of user experience.

New features
  • Huge UX (User eXperience) improvement for all optimization-based tools. Wrapper functions are now available for fid(), pfid(), and fpid_optimize() functions that create a progress window which shows the current parameters, and allow to either stop the identification (or optimization) process while keeping the intermediate search variables, or to abort the process to keep the old values. Moreover, performance history is saved and may be viewed from the PUI (Process UI) later. For FOPID optimization tool the controller parameter change history is also saved and may be used for various purposes, such as choosing different starting points in the parameter search space;
  • A Monte-Carlo method based test simulation facility – testsim() function – is added to check the behavior under parameter uncertainties of a model obtained via time domain identification. It is directly accessible from the fotfid() GUI menu;
  • refgen() class now has basic support for using it in the “From Workspace” Simulink block. See the documentation for the tows() function.
Various improvements
  • Removed the restriction of the stability test using the isstable() function for systems with internal delay. In the current implementation, this restriction was rather artificial and had no effect on stability per se.
NB! The order of the menu items in fotfid() GUI has changed! This was done to make the structure of the menu more logical.

Bug fixes
  • Fixed bug in nyquist() function – lower frequency bound for no argument supplied is now correctly set.
  • fpid_optim() tool was made compatible with most recent MATLAB version.

The updated toolbox can be downloaded in the corresponding section.

Since no changes were introduced into the core functions, toolbox documentation will not be updated with this release. Docs published for v1.0 on this website are valid. To access documentation for new functions, use the usual help() or doc() facilities in MATLAB.

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Commenting Disabled due to Spam Outbreak

Commenting is now globally disabled one the website due to a massive spam outbreak. Unfortunately, this also affects posting on the forums. I cannot tell you now when commenting will be enabled (if ever), but I will work towards making the forums functional again. Sorry for the inconvenience, but it just takes too much time to clear the spam comments off the website.

UPDATE: You can now register on the website (see the “Login/register” tab in the right side column). With a valid registration you can post comments and use the forum. Reporting bugs does not require a registration.

Please note that your registration must be manually approved by the website administrator. This takes at most 1-2 working days. Finally, the administrator has to approve your first comment on the website.

UPDATE (Dec 2018): Registrations are now closed. Existing messages will be preserved until a FAQ is compiled based on the questions asked and answered. Once the FAQ is up, all messages will be deleted along with all registered accounts and all associated user data (name and email).

If you have questions regarding FOMCON, please send them to me directly (you can find contact information on this website). If you find a bug in FOMCON toolbox, please report it via the bug tracker.

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Project updates: August 2015

We would like to announce the launch of FOMCON toolbox for MATLAB version 1.0. This release offers several important features. Since the latest release many bugs have been identified and fixed, and we believe that it is now possible to provide a stable version of the toolbox for download.

Kindly note that all further releases in the 1.x branch will only serve to fix potential bugs as well as introducing minor features. The 2.x branch will be developed in parallel and shall offer even more flexibility in working with fractional systems, models and controllers.

New features
  • Identification tool updates: identification algorithm selection, residual analysis;
  • Parametric identification tool added: see documentation for pfid() function for details;
  • FOPID controller optimization tool updates: setting custom reference signal for reference-based optimization now possible;
  • New convenience function: refgen() for generating identification/reference signals.
Bug fixes
  • Numerous bugs fixed, see the bug tracker for a list of major closed bugs.

In addition, latest developments were added related to published results, including the Simulink retuning controller library. Type retuning_controllers in the MATLAB command prompt to open the library. See the corresponding publication for details.

The updated toolbox can be downloaded in the corresponding section.

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