Adifor 3.0: Architecture, Functionality and Usage
by
Mike Fagan
Rice University, Department of Computational and Applied Mathematics
Coauthors: Alan Carle (Rice University)

This talk introduces Adifor 3.0, a new version of Adifor (Automatic Differentiation of Fortran 77). In addition to the first-order forward mode provided by Adifor 2.0, Adifor 3.0 includes a first order reverse mode and a trio of second order forward modes (U^tHV, V^tHV, and univariate Taylor series). All of these differentiation modes can now be applied to (1) explicitly parallel programs that make use of the MPI (Message Passing Interface) library, (2) programs that write and subsequently read ``active'' data to and from the filesystem, and (3) multidisciplinary systems consisting of a ``pipeline'' of programs. By design, Adifor 3.0 continues to provide automatic differentiation support for ``real world'' Fortran 77 programs with a minimum of user intervention.

Although Adifor 3.0 extends Adifor 2.0 with a substantial amount of new functionality, our goal in developing Adifor 3.0 was to provide users of the system with a means of generating derivative code that is easy to use. Primarily, this entails hiding the concepts of seed matrix initialization and derivative extraction. Users are free to use the ``low-level'' interface and do their own initialization and extraction if they wish. We expect the majority of users will take advantage of our new ``high-level'' interfaces.

We will describe the architecture of the Adifor 3.0 system, the implementation of the underlying automatic differentiation modes, and the new high-level derivative code interfaces.

Adifor 3.0: Architecture, Functionality and Usage

Date received: December 30, 1999