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Title: Utilities for building and optimizing a computational graph for algorithmic decomposition

Technical Report ·
OSTI ID:5617477

This document describes a utility to construct and evaluate an optimized execution graph from the tapefile generated by the ADOL-C automatic differentiation software. It describes the format of the ADOL-C tapefile, the data structures used in building and storing the graph, and the optimizations performed in transforming the computation trace stored in the tape into an efficient graph representation. In particular, we eliminate assignments, increase granularity by hoisting'' chains of unary operations, and remove so-called dead roots -- intermediate values that have no influence on the dependent. Examples show that the optimized graphs contain up to 50% fewer nodes than a graph that would be an exact analogue of the ADOL-C tape. We also describe an attempt at generating compiled code for the graph evaluation as an alternative to interpretative approaches to evaluating the graph. 3 refs., 11 figs., 5 tabs.

Research Organization:
Argonne National Lab., IL (USA)
Sponsoring Organization:
USDOE; National Science Foundation (NSF); USDOE, Washington, DC (USA); National Science Foundation, Washington, DC (USA)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
5617477
Report Number(s):
ANL/MCS-TM-148; ON: DE91013035
Country of Publication:
United States
Language:
English