Aliette Mandelbrot told The New York Times her husband suffered from pancreatic cancer and died Thursday in Cambridge.
Mandelbrot developed the idea of fractals while trying to determine the length of the British coastline, when he realized a seemingly smooth shore becomes more and more detailed as you zoom in. He applied his mathematical insights to areas as diverse as wheat prices and the growth of mammals' brains.
He once said his own life showed the same properties as the coast.
"If you take the beginning and the end, I have had a conventional career," he said. "But it was not a straight line between the beginning and the end. It was a very crooked line."
Mandelbrot was born in Warsaw, moved with his family to France as a child and spent World War II as a farm laborer. After the war, he studied in Paris and the United States, receiving his doctorate in France in 1952.
In 1958, Mandelbrot joined IBM and did research there until his retirement in 1987. He moved on to Yale University, retiring again in 2005.