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Section: Software and Platforms
TAPENADE
Participants : Laurent Hascoet [correspondant] , Valérie Pascual, Ala Taftaf.
tapenade is an Automatic Differentiation tool that transforms an original program into a new program that computes derivatives of the original program. Automatic Differentiation produces analytical derivatives, that are exact up to machine precision. Adjoint-mode AD can compute gradients at a cost which is independent from the number of input variables. tapenade accepts source programs written in Fortran77, Fortran90, or C. It provides differentiation in the following modes: tangent, vector tangent, adjoint, ans vector adjoint. Documentation is provided on the web site of the reserch team http://www-sop.inria.fr/tropics/ , in Inria technical report RT-0300, and in [13] . tapenade runs under most operating systems and requires installation of Java jdk1.6 or upward.
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ACM: D.3.4 Compilers; G.1.0 Numerical algorithms; G.1.4 Automatic differentiation; I.1.2 Analysis of algorithms
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Keywords: automatic differentiation, adjoint, gradient, optimisation, inverse problems, static analysis, data-flow analysis, compilation
tapenade implements the results of our research about models and static analyses for AD. tapenade can be downloaded and installed on most architectures. Alternatively, it can be used as a web server. tapenade differentiates computer programs according to the model described in section 3.1 and in [13] Higher-order derivatives can be obtained through repeated application of tangent AD on tangent- and/or adjoint-mode AD.
tapenade performs sophisticated data-flow analysis, flow-sensitive and context-sensitive, on the complete source program to produce an efficient differentiated code. Analyses include Type-Checking, Read-Write analysis, and Pointer analysis. AD-specific analysis include:
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Activity analysis: Detects variables whose derivative is either null or useless, to reduce the number of derivative instructions.
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Adjoint Liveness analysis: Detects the source statements that are dead code for the computation of derivatives.
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TBR analysis: In adjoint-mode AD, reduces the set of source variables that need to be recovered.
tapenade is not open-source. Academic usage is free. Industrial or commercial usage require a paying license, as detailled on the team's web page. The software has been downloaded several hundred times, and the web tool served several thousands of true connections (not counting robots). The tapenade-users mailing list is over one hundred registered users.