Evelyn Boyd Granville, one of the first Black women to receive a doctorate in mathematics from an American university and whose groundbreaking work in computers included helping calculate orbit trajectories and lunar-landing scenarios for the space program, died June 27 at her home in Silver Spring, Md. She was 99.

The death was announced by a funeral home in Washington. No cause was given.

Dr. Granville specialized in the analysis and interplay of complex equations and variables, a valuable expertise as NASA looked to harness early mainframe computers for an edge in the space race with the Soviet Union.

Recruited in 1956 by IBM to program a data-processing unit, Dr. Granville was part of the company’s team working with NASA after its founding in 1958, a year after the U.S.S.R. launched the Sputnik satellite.

At IBM, Dr. Granville was assigned to the satellite-focused Project Vanguard. “At that time, the satellite was the size of a grapefruit,” she told Scientific American in 2014. “We were writing programs for something up in the air the size of a grapefruit!”

Then she was on the astronaut program Mercury, which in February 1962 successfully launched a rocket with John Glenn aboard as the first American to orbit Earth. Dr. Granville wrote programs to track orbital trajectories, critical calculations that included safe reentry into the atmosphere.

Later, with North American Aviation and IBM, she was part of divisions aiding the Apollo missions, providing technical support to engineers working on Moon landing calculations years ahead of the first steps on the lunar surface in 1969.

“There was such a need for talent,” she told the Tyler Morning Telegraph in Texas in 2000, “that companies stopped looking at race and gender.”

That was true, up to a point. Dr. Granville was part of a small cadre of other Black women involved in the space program, such as the group recounted in the book and 2016 film “Hidden Figures.” But Dr. Granville also knew segregation and sexism firsthand, and she often lamented that women and minorities remained significantly underrepresented in math and sciences.

She spent her childhood in Washington, in the segregated education system. After receiving her doctorate in 1949 from Yale University, she took a teaching position at Fisk University, a historically Black college in Nashville, because she felt professorships at other colleges were effectively closed to Black women at the time.

“We accepted education as the means to rise above the limitations that a prejudiced society endeavored to place upon us,” she wrote in a 1989 essay for the scholarly journal Sage, which focuses on Black women.

Over a career spanning six decades, Dr. Granville embraced reinvention. She taught in a public school in Texas, collaborated on a math textbook used in more than 50 universities and helped her husband raise chickens and catfish at a 16-acre tract in East Texas.

Once asked to list her accomplishments, Dr. Granville said: “First of all, showing that women can do mathematics.” Then she added: “Being an African American woman, letting people know that we have brains, too.”

Proud ‘nerd’

Evelyn Boyd was born in Washington on May 1, 1924. Her father, who worked as a custodian in their apartment building, left the family when she was young. She was raised by her mother and an aunt (her mother’s twin sister), both of whom worked as examiners for the U.S. Bureau of Engraving and Printing. Evelyn and her older sister often spent portions of the summer at the farm of a family friend in Linden, Va.

She was valedictorian in her 1941 graduating class at Dunbar High School and received a partial scholarship to the all-female Smith College in Northampton, Mass. She planned to study French but was soon fascinated by courses in mathematics, physics and astronomy. She returned to Washington during summer break to work at what was then the National Bureau of Standards.

“This whole word they’ve invented, ‘nerd,’ didn’t exist in my day,” she told the Christian Science Monitor in 2002, “thank goodness.”

She received her bachelor’s degree in mathematics from Smith in 1945 and began work at Yale toward her master’s degree (1946) and then doctorate, studying functional analysis of equations and mathematical theory.

Dr. Granville’s doctorate was awarded the same year that another Black woman, Marjorie Lee Browne, finished her doctoral work in mathematics at the University of Michigan. In 1943, Euphemia Lofton Haynes received a doctorate in mathematics from Catholic University in what is widely cited as the first such mathematics degree to a Black woman in the United States. (Black women had earlier doctorates in other academic disciplines.)

“If I had known then that, in the not-too-distant future, the United States would launch its space program, and astronomers would be in great demand in the planning of space missions, I might have become an astronomer instead of a mathematician,” Dr. Granville wrote.

In 1950, Dr. Granville became an associate professor of mathematics at Fisk, where two of her female students went on to complete doctorates in mathematics. She worked from 1952 to 1956 as an applied mathematician at the Diamond Ordnance Fuze Laboratory, a defense industry supplier, before joining IBM.

She moved to Los Angeles in 1960 after her marriage to the Rev. Gamaliel Mansfield Collins. She continued in space flight calculations, first with Space Technology Laboratories and then North American Aviation. She rejoined IBM in 1963 as a senior mathematician for the Apollo project.

She left in 1967 for a teaching position at California State University in Los Angeles, where she described being “shocked” at the math skills of students. She remained in education for the rest of her career, co-writing a college textbook, “Theory and Applications of Mathematics for Teachers” (1975).

She later held positions at Texas College, a historically Black college in Tyler, and the University of Texas at Tyler before her retirement in 2010.

Her first marriage ended in divorce. She and her second husband, a retired real estate broker she met in Los Angeles, Edward Granville, raised chickens on their property near Tyler and sold eggs as well as catfish from the property’s lake. “I was convinced that a move to a rural setting in East Texas would be a welcome change from the Los Angeles metropolis,” she wrote.

Edward Granville died in 2008. She had no children. Information on survivors was not immediately available.

Despite Dr. Granville’s contributions to computer advancements, she saw one spinoff - the humble calculator - as an enemy. She proposed banning calculators in elementary school and returning to classic teaching methods such as long division and multiplication tables.

“The children end up crippled in mathematics at an early age. Then, when they get to the college level, they are unable to handle college classes,” she said. “It’s tragic because almost every academic area requires some exposure to mathematics.”