Lloyd Richard Welch is an American information theorist, and co-inventor of the Baum–Welch algorithm and the Berlekamp–Welch algorithm, also known as the Welch–Berlekamp algorithm.
He is an applied mathematician and a descendant of Carl Gauss.
Welch received his B.S. in mathematics from the University of Illinois, 1951, and Ph.D. in mathematics from the California Institute of Technology, 1958, under advisor Frederic Bohnenblust. He worked at the Jet Propulsion Laboratory 1956–1959, Institute for Defense Analyses, 1959–1965, and University of Southern California, 1965–1999. He is a member of the National Academy of Engineering, IEEE Fellow, and received the 2003 Claude E. Shannon Award.