# Obituary: Hans F. Weinberger

Hans was born in Vienna, Austria, on September 27, 1928. The Weinberger family emigrated to the U.S. in 1938 and eventually settled in Altoona, Pa. Hans was an excellent student and graduated from high school at the age of 16. He was very interested in science and became a finalist in the 1945 Westinghouse Science Talent Search for his design of a self-inflating life vest for the U.S. Navy, which earned him a patent. Hans enrolled as a physics major at the Carnegie Institute of Technology (now Carnegie Mellon University), and received his M.S. in physics in 1948 and his Sc.D. in mathematics in 1950 — at the age of 21. His thesis, entitled “Fourier Transform of Moebius Series,” was supervised by Richard Duffin. Interestingly, the legendary John Nash was Hans’s roommate for one semester; Sylvia Nasar’s *A Beautiful Mind* offers a brief account of their relationship.

After receiving his Sc.D., Hans worked at the University of Maryland, College Park and spent 10 years at its Institute of Fluid Dynamics and Applied Mathematics. In 1960, he joined the faculty of the University of Minnesota as a full professor, serving as department head from 1967 to 1969. He supervised nine Ph.D. students and counted David Gilbarg, Joseph Keller, Lawrence Payne, George Pólya, and Murray Protter among his collaborators. Hans also collaborated locally with Donald Aronson, Leonid Hurwicz (Nobel laureate in economics) and James Serrin, among others. He wrote or coauthored over 140 research papers, with the last appearing in 2015.

Hans published three influential books: *Variational Methods for Eigenvalue Approximation*, based on his Conference Board of the Mathematical Sciences lectures; *Maximum Principles in Differential Equations* with Protter, which was the standard reference for many years; and the widely-used textbook *A First Course in Partial Differential Equations*. In 1986, he was elected as an American Academy of Arts and Sciences member. He was also a member of the inaugural class of American Mathematical Society fellows.

In 1979, in response to the National Science Foundation’s (NSF) request for proposals to establish a new national mathematics research institute, Hans—along with George Sell and Willard Miller, Jr.—submitted a proposal to establish the IMA at the University of Minnesota. They envisioned an institute that would look outward from the core of mathematics towards applications, and unite mathematicians with scientists from industry and other disciplines to work on problems of mutual interest. The proposal—though radical—was funded by the NSF, and Hans served as the institute’s first director from 1982 to 1987. Under his leadership, the IMA quickly became known for its cutting-edge scientific programs; unique, collaborative atmosphere; and reputation as a training ground for postdoctoral researchers. Hans was very much a hands-on director, attending nearly all lectures and collaborating with visitors and postdocs.

As a lifelong member of SIAM, Hans was active in the organization since its inception in 1952. His earliest SIAM publication dates back to 1957, in the *Journal of the Society for Industrial and Applied Mathematics* (the only SIAM journal at the time). He later served on the editorial boards of the *SIAM Journal on Matrix Analysis and Applications* and the *SIAM Journal on Mathematical Analysis*, and was elected to the Board of Trustees in 1983.

Hans was modest and unassuming, but possessed prodigious mathematical talent. His office door was always open, welcoming students, colleagues, and visitors to come in and discuss their current work. Hans was quick to see the essence of any problem and often able to offer extremely helpful comments and suggestions. He was, in sum, an ideal colleague.

Hans is survived by his wife Laura and three children: Catherine, Sylvia, and Ralph.