Pioneering figure in numerical analysis and computation and one of the founders of the Association for Computing Machinery (ACM), Blanch was born Gittel Kaimowitz in Kolno, Russia (now Kolno, Poland), arrived in the United States as a child, and attended public schools in New York City. She spent fourteen years as a clerk, saving money for school. She received her B.S. in mathematics (minor in physics) from New York University in 1932, and her Ph.D. from Cornell University in algebraic geometry in 1935.
For a while she worked as a substitute teacher at Hunter College; then, in 1938, she began work on the Mathematical Tables Project of the WPA, for which she served as technical director. This entailed designing algorithms that were executed by teams of human computers under her direction. Many of these computers possessed only rudimentary mathematical skills, but the algorithms and error checking in the Mathematical Tables Project were sufficiently well designed that their output defined the standard for transcendental function solution for decades. This project later became the Computation Laboratory of the National Bureau of Standards.
During World War II, Blanch worked for the Office for Scientific Research and Development, and she oversaw calculations for the Army, Navy, Manhattan Project, and other institutions. After the war, her career was hampered by FBI suspicions that she was secretly a communist. Their evidence for this seemed scarce, and included, for example, the observation that she had never married or had children. In what must have been a remarkable showdown, the diminutive fifty-year-old mathematician demanded, and won, a hearing to clear her name.
Subsequently, she worked for the Institute for Numerical Analysis at UCLA and the Aerospace Research Laboratory at Wright-Patterson Air Force Base in Dayton, Ohio. She published over thirty papers on functional approximation, numerical analysis, and Mathieu functions. In 1962, she was elected a Fellow of the American Association for the Advancement of Science.
She retired in 1967 at the age of 69, but continued working under a consulting contract for the Air Force for another year. Thereafter Blanch moved to San Diego and continued to work on numerical solutions of Mathieu functions until her death in 1996, concentrating on the use of continued fractions to achieve highly accurate results in a small number of computational steps. This work was not published. The Gertrude Blanch Papers, 1932–1996 are stored at the Charles Babbage Institute, University of Minnesota, Minneapolis.
