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Odyssée: Automatic Differentiation of Fortran Programs

SYNOPSIS:

The Odyssée system produces a Fortran 77 program computing the first order derivatives of a function given as a Fortran 77 program. Information on this system can be found at the Odyssee home page .

WHOM TO CONTACT:

Christele Faure
Projet SAFIR
INRIA Sophia-Antipolis
2004 route des lucioles
BP 93, 06902 Sophia Antipolis Cedex
FRANCE
Christele.Faure@sophia.inria.fr , odyssee@sophia.inria.fr

DOCUMENTATION:

WWW: http://www.inria.fr/safir/SAM/Odyssee/odyssee-bib.html

First paper: N. Rostaing, S. Dalmas, and A. Galligo, Automatic Differentiation in Odyssée, Tellus, 45A, 1993.

FUNCTIONALITY:

The automatic differentiation system Odyssée takes as input a Fortran 77 subroutine or collection of subroutines and produces the corresponding subroutines computing the derivatives in different ways:

Direct mode: Odyssée produces a program computing the tangent linear application (the Jacobian matrix times a vector).
Reverse mode: Odyssée produces a program computing the cotangent linear (or adjoint) application (the transposed Jacobian matrix times a vector).

The Odyssée system can be used via a graphic interface or a shell language.

It accepts some syntax extensions of Fortran 77: include, do while.
For each subroutine, the input variables with respect to which the derivatives will be computed may be arguments of the subroutine or defined in COMMON blocks.
Unlike previous versions, the current version performs interprocedural analysis on the set of routines submitted.

HIGHLIGHTS:

Odyssée is written in a high-level language ( objective CAML , developed at INRIA). It is an extensible system.

Strategies: Different strategies for computing the cotangent linear application have been implemented.
Black Box Routines: The Odyssée system allows to treat a subroutines calling another one whose source code is not available. The user has to give the interprocedural information concerning it, and the system will produce a call to a derivative subroutine written by the user.

Restrictions:

A subroutine containing Goto instructions cannot be differentiated in reverse mode.
The COMMON blocks must be defined in the same way for all routines of the program.
EQUIVALENCEs and POINTERs are not treated by the system.

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