Gertrude Blanch was a brilliant and driven mathematician, responsible for the definitive mathematical tables used by mathematicians, scientists, and industry in the decades before the introduction of interactive computers.

Women were central to the development of early computers, mostly in the design and production of software. Blanch's work was purely in the development of algorithms; she established her ability to design efficient methods for calculating the values of mathieu functions, transcendental functions and the like as early as 1938, well before the first digital computer had even been built.

She did this as technical director of the Mathematical Tables Project, a U.S. government project to create definitive printed values for a large number of functions. Younger readers may not believe this, but prior to the mid-1970s, if you wanted to know the answer to Sin(1.77) or arcTan(1.001), you looked it up in a book. There were many different volumes for different functions, some based on work done hundreds of years ago, and most contained many errors. During the Great Depression, the U.S. goverment hired Blanch to develop a definitive set of tables, wiping out all the lesser work.

The "Math Tables Project", as it was known, involved 450 human 'computers' who followed steps specified by Blanch to produce and check the answers to millions of math problems. Ultimately, they produced 28 volumes of tables, each the size of a large dictionary. Many of these books contain no known errors. (I own a near-complete set of their work, and it is wonderful to flip open a volume and see these rows of numbers. They represent the determination of humans to master the natural world.)

Blanch had entered mathematics late in life. She was born in Poland in 1897 and emigrated to the United States in 1907, speaking no English. Nonetheless, she graduated from high school in 1914 and spent the next 14 years working as a clerk to save money for higher education. She enrolled in NYU night school in 1928 and graduated four years later, Summa Cum Laude, a member of Phi Beta Kappa. She wrote her doctoral dissertation on Properties of the Veneroni Transformation in S4, and received her Ph.D. from Cornell University in Analytic Geometry in 1936, at the age of 39.

I believe that it was at this time, in pursuit of employment opportunities not available to Jews, that she changed her name from "Kaimowitz" to "Blanch". She worked in minor jobs for two years before landing the job with the Math Tables Project.

Tables were of vital importance during World War II, and Blanch's skills were in high demand. Soldiers firing mortars, pilots dropping bombs, scientists designing atomic bombs, all needed quick answers to complex mathematical problems. Computers were not available, so the problems were given to the Math Tables Project, which returned fully worked solutions for the entire range of possible inputs that end-users might encounter.

Blanch oversaw calculations for the Army, Navy, Manhattan Project and dozens of defense industries. After the war, she joined first the Institute for Numerical Analysis at UCLA and from 1954 she served as senior mathematician at the Aerospace Research Laboratory at Wright-Patterson Air Force Base. She published over thirty papers on functional approximation, numerical analysis and Mathieu functions. She was elected a Fellow in the American Association for the Advancement of Science in 1962 and was given the Federal Woman's Award from President Lyndon Johnson in 1964.

Gertrude never married and never had children. She was forced into retirement in 1967, at the age of 69, but was given a consulting contract by the Air Force. This contract expired in 1970, but she continued to work on numerical solutions to mathieu functions until her death in 1996, concentrating on the use of continued fractions to achieve high accuracy results in a small number of computational steps. This work has not been published.

In the *Blanch Anniversary Volume*, published on the occasion of her retirement on February 21, 1967, computing great Ida Rhodes contributed a paper called "The Mighty Man-Computer Team", which she dedicated by saying

"This talk, which was delivered at a meeting of the Fall Joint Computing Conference, is dedicated to Gertrude Blanch, my brilliant mentor and most beloved friend. She has always exemplified for me everything that is noble, true, and admirable in a human being. To her I owe whatever success I have achieved in my career..."

**Sources:**

Grier, D. A. "Gertrude Blanch of the Mathematical Tables Project," Annals of the History of Computing

Many personal discussions with Gertude, 1987-1996

Blanch Anniversary Volume, February 21, 1967