Various derivative estimates for functions of exponential type in a half-plane are proved in this paper. The reader will also find a related result about functions analytic in a quadrant. In addition, the paper contains a result about functions analytic in a strip. Our main tool in this study is the Schwarz-Pick theorem from the geometric theory of functions. We also use the Phragmén-Lindelöf principle, which is of course standard in such situations.
@article{bwmeta1.element.doi-10_2478_v10062-011-0021-6, author = {M. Qazi and Q. Rahman}, title = {The Schwarz-Pick theorem and its applications}, journal = {Annales UMCS, Mathematica}, volume = {65}, year = {2011}, pages = {149-167}, zbl = {1273.30001}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.doi-10_2478_v10062-011-0021-6} }
M. Qazi; Q. Rahman. The Schwarz-Pick theorem and its applications. Annales UMCS, Mathematica, Tome 65 (2011) pp. 149-167. http://gdmltest.u-ga.fr/item/bwmeta1.element.doi-10_2478_v10062-011-0021-6/
Ahlfors, L. V., Conformal Invariants: Topics in Geometric Function Theory, McGraw-Hill Book Company, New York-Düsseldorf-Johannesburg, 1973.
Bernstein, S. N., Sur la limitation des dérivées des polynomes, C. R. Math. Acad. Sci. Paris 190 (1930), 338-340. | Zbl 56.0301.02
Boas, Jr., R. P., Entire Functions, Academic Press, New York, 1954.
Carathéodory, C., Conformal Representation, Cambridge Tracts in Mathematics and Mathematical Physics, No. 28, Cambridge University Press, Cambridge, 1963. | Zbl 58.0354.14
Krzyż, J. G., Problems in Complex Variable Theory, American Elsevier Publishing Company, Inc., New York, 1971. | Zbl 0239.30001
Qazi, M. A., Rahman, Q. I., Some estimates for the derivatives of rational functions, Comput. Methods Funct. Theory 10 (2010), 61-79. | Zbl 1194.30030
Qazi, M. A., Rahman, Q. I., Functions of exponential type in a half-plane, Complex Var. Elliptic Equ. (in print). | Zbl 1291.30006
Rahman, Q. I., Inequalities concerning polynomials and trigonometric polynomials, J. Math. Anal. Appl. 6 (1963), 303-324. | Zbl 0122.25302
Rahman, Q. I., Schmeisser, G., Analytic Theory of Polynomials, Clarendon Press, Oxford, 2002. | Zbl 1072.30006