Section: New Results

AD-adjoints of Iterative Processes

Participants : Laurent Hascoët, Ala Taftaf, Sri Hari Krishna Narayanan [Argonne National Lab. (Illinois, USA)] , Daniel Goldberg [University of Edinburgh, UK] .

Ala Taftaf continued her work on the adjoint of iterative Fixed-Point loops. This year she studied refinements of the AD-specific data-flow analyses to adapt them to the specific shape of this adjoint code, proposed by Bruce Christianson  [27]. She also proposed an efficient “warm-start” mechanism, that provides a good initial guess for the fixed-point loop that computes the adjoint, in the case where this fixed-point loop is itself enclosed in another loop. These results are described in her PhD document, to be defended in January 2017.

We published a journal article [13] on our joint work with Krishna Narayanan from ANL and Dan Goldberg from University of Edinburgh (UK), which applies in particular this fixed-point adjoint strategy to a glaciology configuration of the MIT GCM code.