# Sueli I. Rodrigues Costa

• 2003
We consider two codes based on dynamical systems, for transmitting information from a continuous alphabet, discrete-time source over a Gaussian channel. The first code, a homogeneous spherical code, is generated by the linear dynamical system s/spl dot/=As, with A a square skew-symmetric matrix. The second code is generated by the shift map s/sub n/=b/sub(More)
• 3
• 2015
This paper is a strongly geometrical approach to the Fisher distance, which is a measure of dissimilarity between two probability distribution functions. The Fisher distance, as well as other divergence measures, are also used in many applications to establish a proper data average. The main purpose is to widen the range of possible interpretations and(More)
• Paulo F. de Santa, Shin -Ting
• 1997
This paper explores the use of elements of Diierential Geometry to control the manipulation of the deformable model proposed by Terzopoulos et al. 8] for animating deformable objects. Particularly, we are interested on the animation of deformable panels without stretching (area invariant), such as clothes and papers. Based on our analysis we could generate(More)
Twisted curves in R' are those which have independent derivatives up to order m. For plane and spatial curves the twisted condition is equivalent to never vanishing curvature and torsion respectively. We give a necessary and sufficient condition for a (q, p)-curve on a torus to be twisted, and use those curves to construct closed twisted curves in R'" for(More)
• 2016
We investigate perfect codes in Z n in the p metric. Upper bounds for the packing radius r of a linear perfect code in terms of the metric parameter p and the dimension n are derived. For p = 2 and n = 2, 3, we determine all radii for which there exist linear perfect codes. The non-existence results for codes in Z n presented here imply non-existence(More)
• 2013
The foliation of a sphere in an even number of dimensions by flat tori can be used to construct discrete spherical codes and also homogeneous curves for transmitting a continuous alphabet source over an AWGN channel. In both cases the performance of the code is related to the packing density of specific lattices and their orthogonal sublattices. In the(More)
• 1
• 2004
Quadrature amplitude modulation (QAM)-like signal sets are considered in this paper as coset constellations placed on regular graphs on surfaces known as flat tori. Such signal sets can be related to spherical, block, and trellis codes and may be viewed as geometrically uniform (GU) in the graph metric in a sense that extends the concept introduced by(More)
• 2011
Q-ary lattices can be obtained from q-ary codes using the so-called Construction A. We investigate these lattices in the Lee metric and show how their decoding process can be related to the associated codes. For prime q we derive a Lee sphere decoding algorithm for q-ary lattices, present a brief discussion on its complexity and some comparisons with the(More)
• 2015
A method for finding an optimum n-dimensional commutative group code of a given order M is presented. The approach explores the structure of lattices related to these codes and provides a significant reduction in the number of non-isometric cases to be analyzed. The classical factorization of matrices into Hermite and Smith normal forms and also basis(More)