Altres
http://hdl.handle.net/2117/5344
2015-10-13T09:05:19ZPrácticas complementarias al curso de Matemáticas II al tema de las derivadas parciales: Procesamiento digital de imágenes
http://hdl.handle.net/2117/76336
Prácticas complementarias al curso de Matemáticas II al tema de las derivadas parciales: Procesamiento digital de imágenes
Acho Zuppa, Leonardo
Documento docente sobre algunas aplicaciones de las derivadas parciales al procesamiento digital de imágenes.
Documento docente sobre algunas aplicaciones de las derivadas parciales al procesamiento digital de imágenes.
2015-04-08T00:00:00ZDynamics of integrable birational maps preserving genus 0 foliations
http://hdl.handle.net/2117/24431
Dynamics of integrable birational maps preserving genus 0 foliations
Llorens, Mireia; Mañosa Fernández, Víctor
Pòster presentat al congrés NPDDS2014
2014-10-03T00:00:00ZPeriodic orbits of integrable birational maps on the plane: blending dynamics and algebraic geometry, the Lyness' case
http://hdl.handle.net/2117/16795
Periodic orbits of integrable birational maps on the plane: blending dynamics and algebraic geometry, the Lyness' case
Bastien, Guy; Mañosa Fernández, Víctor; Rogalski, Marc
Contingut del Pòster presentat al congrés New Trends in Dynamical Systems
2012-10-01T00:00:00ZGlobal periodicity conditions for maps and recurrences via Normal Forms
http://hdl.handle.net/2117/15947
Global periodicity conditions for maps and recurrences via Normal Forms
Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor
We face the problem of characterizing the periodic cases in parametric families of (real or complex) rational diffeomorphisms having a fixed point. Our approach relies on the Normal Form Theory, to obtain necessary conditions for the existence of a formal linearization of the map, and on the introduction of a suitable rational parametrization of the parameters of the family. Using these tools we can find a finite set of values p for which the map can be p-periodic, reducing the problem of finding the parameters for which the periodic cases appear to simple computations. We apply our results to several two and three dimensional classes of polynomial or rational maps. In particular we find the global periodic cases for several Lyness type recurrences
2012-05-04T00:00:00ZOn periodic solutions of 2-periodic Lyness difference equations
http://hdl.handle.net/2117/14440
On periodic solutions of 2-periodic Lyness difference equations
Bastien, Guy; Mañosa Fernández, Víctor; Rogalski, Marc
We study the existence of periodic solutions of the non--autonomous periodic Lyness' recurrence u_{n+2}=(a_n+u_{n+1})/u_n, where {a_n} is a cycle with positive values a,b and with positive initial conditions. It is known that for a=b=1 all the sequences generated by this recurrence are 5-periodic. We prove that for each pair (a,b) different from (1,1) there are infinitely many initial conditions giving rise to periodic sequences, and that the family of recurrences have almost all the even periods. If a is not equal to b, then any odd period, except 1, appears.
Preprint
2012-01-04T00:00:00ZIntegrability and non-integrability of periodic non-autonomous Lyness recurrences (revised and enlarged version)
http://hdl.handle.net/2117/14345
Integrability and non-integrability of periodic non-autonomous Lyness recurrences (revised and enlarged version)
Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor
This paper studies non-autonomous Lyness type recurrences of the form xn+2 = (an+xn+1)=xn, where fang is a k-periodic sequence of positive numbers with primitive period k. We show that for the cases k 2 f1; 2; 3; 6g the behavior of the sequence fxng is simple (integrable) while for the remaining cases satisfying this behavior can be much more complicated (chaotic). We also show that the cases where k is a multiple of 5 present some di erent features.
Preprint. Versió revisada i augmentada d'un anterior report homònim.
2011-12-22T00:00:00ZIntegrability and non-integrability of periodic non-autonomous Lyness recurrences
http://hdl.handle.net/2117/10770
Integrability and non-integrability of periodic non-autonomous Lyness recurrences
Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor
This paper studies non-autonomous Lyness type recurrences of the form x_{n+2}=(a_n+x_n)/x_{n+1}, where a_n is a k-periodic sequence of positive numbers with prime period k. We show that for the cases k in {1,2,3,6} the behavior of the sequence x_n is simple(integrable) while for the remaining cases satisfying k not a multiple of 5 this behavior can be much more complicated(chaotic). The cases k multiple of 5 are studied separately.
Preprint arXiv:1012.4925
2010-12-22T00:00:00ZRational periodic sequences for the Lyness recurrence
http://hdl.handle.net/2117/7135
Rational periodic sequences for the Lyness recurrence
Gasull Embid, Armengol; Mañosa Fernández, Víctor; Xarles Ribas, Xavier
Consider the celebrated Lyness recurrence $x_{n+2}=(a+x_{n+1})/x_{n}$ with $a\in\Q$. First we prove that there exist initial conditions and values of $a$ for which it generates periodic sequences of rational numbers with prime periods $1,2,3,5,6,7,8,9,10$ or $12$ and that these are the only periods that rational sequences $\{x_n\}_n$ can have. It is known that if we restrict our attention to positive rational values of $a$ and positive rational initial conditions the only possible periods are $1,5$ and $9$. Moreover 1-periodic and 5-periodic sequences are easily obtained. We prove that for infinitely many positive values of $a,$ positive 9-period rational sequences occur. This last result is our main contribution and answers an open question left in previous works of Bastien \& Rogalski and Zeeman. We also prove that the level sets of the invariant associated to the Lyness map is a two-parameter family of elliptic curves that is a universal family of the elliptic curves with a point of order $n, n\ge5,$ including $n$ infinity. This fact implies that the Lyness map is a universal normal form for most birrational maps on elliptic curves.
2010-04-30T00:00:00ZOn two and three periodic Lyness difference equations
http://hdl.handle.net/2117/6893
On two and three periodic Lyness difference equations
Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor
We describe the sequences {x_n}_n given by the non-autonomous second order Lyness difference equations x_{n+2}=(a_n+x_{n+1})/x_n, where {a_n}_n is either a 2-periodic or a 3-periodic sequence of positive values and the initial conditions x_1,x_2 are as well positive. We also show an interesting phenomenon of the discrete dynamical systems associated to some of these difference equations: the existence of one oscillation of their associated rotation number functions. This behavior does not appear for the autonomous Lyness difference equations.
2009-12-26T00:00:00Z