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Section: New Software and Platforms
TAPENADE
Participants : Laurent Hascoët [correspondant] , Valérie Pascual, Ala Taftaf, Jan Hueckelheim [Queen Mary University of London] .
Tapenade is an Algorithmic Differentiation tool that transforms an original program into a new program that computes derivatives of the original program. Algorithmic 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, and vector adjoint. Documentation is provided on http://www-sop.inria.fr/tropics/tapenade.html , in Inria technical report RT-0300, and in [9] .
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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: algorithmic 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. Higher-order derivatives can be obtained through repeated application.
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 analyses 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 for one year. Other usages require a paying license, as detailled on the web page. Ten industrial licences have been sold. Tapenade has been downloaded several hundred times, and the web tool served several thousands of true connections (robots and crawlers excluded) The tapenade-users mailing list is over one hundred registered users.