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Adams/Solver
Computing Partial Derivatives
The computation of the partial derivatives of a complicated FORTRAN subroutine can be an
overwhelming task. MSC investigated the software, Automatic Differentiation of FORTRAN
(ADIFOR), that may be able to automate this task.
ADIFOR is a tool for automatic computation of derivatives of function defined in FORTRAN 77
programs.
Automatic differentiation is a technique for computing the derivatives of functions described by
computer programs. ADIFOR implements automatic differentiation by transforming a collection of
FORTRAN 77 subroutines that compute a function f into new FORTRAN 77 subroutines that compute
the derivatives of the outputs of f with respect to a specified set of inputs of f.
ADIFOR 2.0 consists of:
• ADIFOR Preprocessor
• ADIntrinsics template expander and library
• SparsLinC library.
Figure 1 shows a block diagram of the ADIFOR 2.0 process, which consists of three steps:
1. Apply the ADIFOR Preprocessor to your FORTRAN 77 program to produce augmented code for
the computation of derivatives. The preprocessor invokes the ADIntrinsics template expander
directly.
2. Construct a derivative driver code that invokes the generated derivative code and uses the
computed derivatives.
3. Compile the generated derivative code and your derivative driver code, and link these with the
derivative support packages. That is, the ADIntrinsics exception handling package and
(optionally) the SparsLinC sparse derivative package.
Figure 1. Block Diagram of the ADIFOR Process