6 papers
Hyperspherical Trigonometry and Corresponding Elliptic Functions
Paul Jennings, Frank Nijhoff
We develop the basic formulae of hyperspherical trigonometry in multidimensional Euclidean space, using multidimensional vector products, and their conversion to identities for ell…
Elliptic solutions of the lattice CKP equation and its elliptic direct linearisation scheme
Ying-ying Sun, Da-jun Zhang, Frank Nijhoff
A direct linearisation scheme, based on an elliptic Cauchy kernel, is set up for the lattice CKP equation. This leads to an elliptic parametrisation of the lattice CKP equation, to…
Discrete integrable principal chiral field model and its involutive reduction
Jan L. CieÅliÅski, Alexander V. Mikhailov, Maciej Nieszporski +1
We discuss an integrable discretization of the principal chiral field models equations and its involutive reduction. We present a Darboux transformation and general construction of…
The elliptic lattice KdV system revisited
Frank Nijhoff, Cheng Zhang, Da-jun Zhang
In a previous paper [Nijhoff,Puttock,2003], a 2-parameter extension of the lattice potential KdV equation was derived, associated with an elliptic curve. This comprises a rather co…
Lagrangian 1-form structure of Calogero-Moser type systems
Thanadon Kongkoom, Frank W. Nijhoff, Sikarin Yoo-Kong
We consider the variational principle for the Lagrangian 1-form structure for long-range models of Calogero-Moser (CM) type. The multiform variational principle involves variations…
QRT Map on a Bielliptic Surface
Nalini Joshi, Frank W. Nijhoff, Allan Steel
The family of mappings of the plane possessing a biquadratic invariant, which is known collectively as QRT maps, is composed of two involutions, one preserving a vertical shift and…