2001/03/26 by S. A. Avdonin, Avdonin, S. A., S. A. Ivanov +1 · 1 citation
Mathematics · #42C15 #FOS: Mathematics #Functional Analysis (math.FA) #math.FA #msc:42C15
paper · pdf · doi:10.48550/arxiv.math/0103160
LaTeX, 19 pages
arxiv created 2001/03/26 · arxiv updated 2009/11/30
Linear combinations of exponentials eiλkt in the case where the distance between some points λk tends to zero are studied. D. Ullrich has proved the basis property of the divided differences of exponentials in the case when the groups consist of equal number of points all of them are close enough to integers. We have generalized this result for groups with arbitrary number of close points and obtained a full description of Riesz bases of exponential divided differences. The application to a control problem is presented.