Shizuo Kambayashi/Associated Press
Benoit B. Mandelbrot at a conference in Tokyo in 2003.
His death was caused by pancreatic cancer, his wife, Aliette, said. He had lived in Cambridge.
Dr. Mandelbrot coined the term “fractal†to refer to a new class of mathematical shapes whose uneven contours could mimic the irregularities found in nature.
“Applied mathematics had been concentrating for a century on phenomena which were smooth, but many things were not like that: the more you blew them up with a microscope the more complexity you found,†said David Mumford, a professor of mathematics at Brown University. “He was one of the primary people who realized these were legitimate objects of study.â€