## David H. Bailey## "Computo ergo sum."## http://www.davidhbailey.com |

- Senior Scientist (retired), Computational Research Department, Lawrence Berkeley National Laboratory. Bailey officially retired from LBNL effective 27 June 2013, but continues as an active researcher.
- Research Associate, Department of Computer Science, University of California, Davis (February 2013 - present).

*Computational and experimental mathematics*. Bailey is also a leading figure in the field of computational and experimental mathematics, applying high performance computing to problems in research mathematics. He is author or co-author of five books and over 100 papers in this field, many of them in conjunction with his long-time collaborator Jonathan M. Borwein of the University of Newcastle, Australia. Bailey is also a co-author of two widely used high-precision computation software packages. His best-known paper in this area, "On the Rapid Computation of Various Polylogarithmic Constants," co-authored with Peter Borwein (Jonathan Borwein's brother) and Simon Plouffe, describes a new formula for pi that permits one to directly calculate binary digits of pi beginning at an arbitrary starting position (this formula was discovered using Bailey's computer implementation of the PSLQ algorithm). In two more recent papers, Bailey and the late Richard Crandall demonstrated a connection between these formulas and a fundamental question about digit randomness. Bailey has received the Chauvenet Prize and the Merten Hesse Prize from the Mathematical Association of America.

*Financial mathematics*. Bailey, together with his colleagues Jonathan Borwein (of the University of Newcastle, Australia), Marcos Lopez de Prado (of Guggenheim Partners) and Jim Qiji Zhu (of Western Michigian University), have written a series of papers on mathematical finance. Their best-known paper in this area, "Pseudo-Mathematics and Financial Charlatanism: The Effects of Backtest Overfitting on Out-of-Sample Performance," has attracted considerable interest in the field (see Press reports for details).

*Other activities*. Bailey and his colleague Jonathan Borwein jointly operate a website devoted to experimental mathematics. They also write articles on mathematics and science for the Math Drudge blog and contribute articles to the Huffington Post and the Conversation. More recently, Bailey, Borwein, Marcos Lopez de Prado and Jim Qiji Zhu have instituted a website and blog devoted to financial mathematics and the misuse of mathematics in the field.

See Books directory for a list of published books, and Papers directory for a full list of over 200 technical papers, including web links to preprint copies.

**Books**. Bailey has written one book on performance science, five books on computational and experimental mathematics, and a CD-ROM reference. All of these books are available at Amazon.com or directly from the respective publishers. Additional information on these books is available here:**Conversation articles**. Bailey and his colleague Jonathan Borwein have authored articles for*The Conversation*, an international forum of academic research and discussion based in Melbourne, Australia. A listing of these articles is available here:**Disclaimer and copyright**. This site is owned and operated by David H. Bailey. Material on this site is provided for research purposes only, and does not necessarily reflect the views or policies of the Lawrence Berkeley National Lab, the University of California, Davis or any other organization. Except where explicitly stated otherwise, all material on this site is copyrighted by David H. Bailey (c) 2016.**Experimental Mathematics website**. Bailey has published numerous research studies in the area of "experimental" (computer-assisted) mathematics, which establish that modern high-performance computer technology can be effectively utilized as a tool for mathematical research. Here is a website with additional information:**Financial Mathematics website**. Bailey and Borwein, together with their colleagues Marcos Lopez de Prado of Hess Energy Trading Co. and Qiji Jim Zhu of Western Michigan University, have recently written a series of papers in mathematical finance, with the objective of helping researchers and investors distinguish mathematically sound techniques from the unfortunately much larger body of questionable techniques that sadly pervade the finance community and financial news. Here is a website with additional information:**High-precision software library**. Bailey is a co-author of several software libraries for high-precision computation. These libraries include translation facilities so that one can use, with minor modifications, ordinary Fortran or C++ programs to perform high-precision calculations:**Huffington Post articles**. Bailey and his colleague Jonathan Borwein have authored articles for the*Huffington Post*, a popular news and information based in the U.S. that was recently named the world's most influential blog/news site in a U.K. Guardian article. A listing of these articles is available here:**Math Drudge blog**. Bailey and his collaborator Jonathan Borwein, jointly operate the "Math Drudge" blog, which contains essays, news and other material in the realm of mathematics, computing and scientific research:**Mathematical Investor blog**. Bailey and Borwein, together with their colleagues Marcos Lopez de Prado and Qiji Jim Zhu, operate the "Mathematical Investor" blog, which contains essays, news and other material in the realm of financial mathematics and related disciplines:**Online papers**. Online copies of over 180 of Bailey's technical papers are available here:**Online talks**. Online copies of many of Bailey's recent lectures are available here:**Personal website**. Some articles, papers, photos and other materials not directly related to Bailey's scientific research work are available at this website:**Photos**.- Photo of Bailey with pi banner (as shown at the top of this page): DHB pi banner
- High-resolution version of full pi banner: DHB pi banner (large)
- Photo of Bailey with an LBNL shuttle bus displaying pi poster: Shuttle bus
- Photo of an auto previously owned by Bailey, together with several researchers involved in calculations of pi (Yasumasa Kanada, Eugene Salamin and William Gosper): Auto photo
- Photo of the view from a spot at LBNL to downtown San Francisco: View from LBNL
- Personal photo of Bailey (12 Kbyte): Bailey photo -- 12 Kbyte
- Personal photo of Bailey (1 Mbyte): Bailey photo -- 1 Mbyte
- Bailey near summit of Half Dome: Bailey at Half Dome

**Pi**. In 1996, Peter Borwein (brother of Jonathan Borwein), Simon Plouffe and Bailey co-authored a paper that presents a new formula for pi:

This formula, now known as the "BBP formula for pi", permits one to compute binary or hexadecimal digit of pi beginning at an arbitrary starting position n, without needing to compute any of the first n-1 digits, by means of a simple scheme that requires very little memory. It was originally discovered by Simon Plouffe using a computer program written by Bailey that implements a simplified version of Helaman Ferguson's "PSLQ" algorithm. More recently, Richard Crandall and Bailey have shown that there is a connection between the new pi formula and the centuries-old question of normality (ie, statistical randomness of digits in a certain sense) of pi and various other math constants.Some additional information on pi:

- Bailey's pi website: http://www.davidhbailey.com/pi
*Science News*article (April 24, 2004): PDF (5 Mbyte)*Scientific American*article (May 2003): PDF- See if your name is coded in the first four billion binary digits of pi: http://pi.nersc.gov
- Fax to Bailey from "The Simpsons" TV show:
PDF.

Note: The 40,000th digit of pi was provided to the show by Bailey, and this was aired in the show on 6 May 1993 -- search for "Marge in Chains" at Simpson math website.

**Press reports**. Here are some press reports mentioning Bailey:**Resume**. Bailey's detailed curriculum vitae (resume), including a list of publications, is available here:**Websites of interest**- Jonathan Borwein's website -- interesting links on general mathematics and experimental mathematics: Jonathan Borwein's website
- Peter Borwein's website -- lots of information on pi and number theory: Peter Borwein's website
- James Demmel's website -- lots of information on computational linear algebra and computer science: James Demmel's website
- Helaman Ferguson's website -- numerous photos of his beautiful mathematical sculptures: Helaman Ferguson's website