Ref-indic: invert details only where they are worth it

Version 1.5+pl0

Outline

Ref-indic, Refinement indicators, is an adaptive parameterization platform using refinement indicators.

Description

The refinement indicator algorithm is suited for the estimation of a distributed parameter occurring in a mathematical simulation model, typically a set of partial differential equations. When the numerical simulation model must be solved on a fine grid, the refinement indicator algorithm provides an adaptive parameterization of the saught parameter that avoids overparameterization difficulties. In each grid cell, the estimated parameter may be of dimension greater than one, i.e. the algorithm is able to estimate several scalar distributed parameters.

Ref-indic implements a generic version of the refinement indicator algorithm that can dock specific programs provided they conform to the generic algorithm API.

The API of Ref-indic requires four main functionalities (called tasks) for the user specific program, it must be able:

• to initialize, i.e. to open all necessary data files, to perform all necessary preliminary computation, and to return an initial coarse parameterization (giving a zone number between 0 and the initial number of zones minus one for each cell of the fine grid);
• to compute the gradient on the fine grid for a given fine parameterization;
• to optimize the problem for a given coarse parameterization;
• and to finalize, i.e. to store the resulting coarse parameterization.

Given any such user specific program, the inversion platform automatically provides a program that solves the corresponding user inverse problem using the refinement indicator algorithm.

In its current implementation, the inversion platform can only build coarse parameterizations for a distributed parameter defined on a fine rectangular grid. From version 1.5+pl0, the user has the possibility to specify masked cells in the fine rectangular grid that will be ignored by the algorithm (with the use of the specific zone number -1 in the initial coarse parameterization). This allows for the treatment of inverse problems defined on unstructured meshes. The handling of both-way interpolations must be taken care of by the gradient computation and optimization tasks. The masked cells must be the same for all components of the parameter.

Documentation

The Ref-indic user's manual is available on line.

You can also download the manual as DVI, PS, and PDF files.

The manual only exists in the English version, volunteers to translate it are warmly welcome...

Talks/papers

• 2011, H. Ben Ameur, G. Chavent, F. Clément, and P. Weis, Image Segmentation with Multidimensional Refinement Indicators, Inverse Problems in Science and Engineering, 19, pp. 577-597 (pre-published in Technical Report 7446, Inria).
• 2008, H. Ben Ameur, F. Clément, P. Weis, and G. Chavent, The Multi-Dimensional Refinement Indicators Algorithm for Optimal Parameterization, Journal of Inverse and Ill-Posed Problems, 16, pp. 107-126 (pre-published in Technical Report 5940, Inria).

Installation

You will need OCaml version 4.01 or higher to build Ref-indic (this software is tested under Linux and Mac OS X up to OCaml version 4.06).

See the INSTALL file provided in the distribution for installation tips.

Download

The latest version (1.5+pl0) of the sources of Ref-indic are available via HTTP.

See the CHANGES file provided in the distribution.

Support

If you find a bug in Ref-indic, please write to <refinement-bugs at inria.fr>.

If you want to get in touch with the implementors of Ref-indic (to contribute some new ideas or lines of code), please write to <refinement-devel at inria.fr>.

If you want to get in touch with the users of Ref-indic, please write to <refinement-users at inria.fr>.

License

This program is free software distributed under the 3-clause BSD license. See the LICENSE file provided in the distribution.

Authors

The version 1.5+pl0 of Ref-indic was developed from 2013 to 2017 by

Hend Ben Ameur <hbenameur at yahoo.ca>,

François Clément <Francois.Clement at inria.fr>, and

Pierre Weis <Pierre.Weis at inria.fr>.

Acknowledgments

The algorithm implemented in Ref-indic comes from papers co-written with Guy Chavent <Guy.Chavent at inria.fr>.

Ref-indic is entirely written in OCaml.

Page generated by fclement on lamerluche at 2017-11-26T17:42:38Z.
Latest update of the content of this page: Sunday, November 26th, 2017.
Copyright © 2013-2017 Institut National de Recherche en Informatique et en Automatique (INRIA), all rights reserved.