Calderón is known for his revolutionary work in the field of analysis, particularly in the area of partial differential equations.His influence helped turn the 1950s trend toward abstract mathematics back in a more practical direction. His award-winning research in the area of integral operators is an example of his impact on contemporary mathematical analysis. During his 45-year career, Calderón produced a number of seminal results and techniques. His accomplishments have been recognized by such prestigious awards as the National Medal of Science and the Wolf Prize in mathematics, and he was a member of the national academies of science of five countries as well as the Third World Academy of Sciences based in Italy. When Calderón was awarded the Steele Prize for a Fundamental Paper in mathematics, his work was described in the Notices of the American Mathematical Society as "a...