The Digital Library of Mathematical Functions (DLMF) Project was initiated to perform a complete revision of Abramowitz and Stegun’s Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, published in 1964 by the National Bureau of Standards. See R. F. Boisvert and D. W. Lozier (2001) for historical background about this important publication. The DLMF Project has updated and expanded the coverage for current needs. The results have been published in book form as the NIST Handbook of Mathematical Functions, by Cambridge University Press, and disseminated in the free electronic Digital Library of Mathematical Functions. For further details about the project see Preface.