Walter Edwin Arnoldi (December 14, 1917 – October 5, 1995) was an American engineer mainly known for the Arnoldi iteration, an eigenvalue algorithm used in numerical linear algebra. His main research interests included modelling vibrations, acoustics, aerodynamics of aircraft propeller, and oxygen reclamation problems of space science. His 1951 paper The principle of minimized iterations in the solution of the eigenvalue problem is one of the most cited papers in numerical linear algebra.[1]