David Harold Bailey (born 14 August 1948) is a mathematician and computer scientist.

This Bailey–Borwein–Plouffe formula permits one to calculate binary or hexadecimal digits of pi beginning at an arbitrary position, by means of a simple algorithm.

Subsequently, Bailey and Richard Crandall showed that the existence of this and similar formulas has implications for the long-standing question of "normality"[2]—whether and why the digits of certain mathematical constants (including pi) appear "random" in a particular sense.

He has published studies on the fast Fourier transform (FFT), high-precision arithmetic, and the PSLQ algorithm (used for integer relation detection).

He is a co-author of the NAS Benchmarks, which are used to assess and analyze the performance of parallel scientific computers.