Address.
Katedra matematickej analyzy a numerickej matematiky,
Fakulta
matematiky, fyziky a informatiky UK, Mlynska dolina, 842,
48 Bratislava, Slovak Republic
E-mail. kubacek@fmph.uniba.sk
Abstract.
For a generalized pendulum equation we estimate the number of
periodic solutions from below using lower and upper solutions and
from above using a complex equation and Jensen's inequality.
AMSclassification. 34B15, 34C25.
Keywords. Generalized pendulum, number of solutions, Jensen's inequality.