Ms. Resnick’s 1981 portraits of John Belushi were the last taken before he died the following year. Marcia Resnick, via Deborah Bell Photographs, New York and Paul M. Hertzmann, Inc., San Francisco.

In tandem, Lipschitz classes serve as a tool for gauging the smoothness and regularity of functions by imposing conditions on the rate at which function values may change.

Marcia Resnick, a photographer known for documenting Manhattan's downtown art scene during the late 1970s and early 1980s, died at age 74. Her cause of death was lung cancer, according to her ...