Introduction. The non-commutative operational formula Dx = xD + 1, where D = d/dx, is well known. The difficulty of determining the order of the operations x and D in a function f (x, D) retarded the use of operative functions. Bourlet1 was the first to discover a way to express an operative function, f(x, D) such that the operations with D always precede those with x. Thus his operators obey the laws of algebra and their operational meaning is unique.
Proceedings of the Iowa Academy of Science
©1940 Iowa Academy of Science, Inc.
Proceedings of the Iowa Academy of Science, 47(1), 277-281.
Available at: https://scholarworks.uni.edu/pias/vol47/iss1/68