A common problem for experimental space physicists is the determination of the "attitude matrix" T which transforms vectors between representations in X and Xl coordinate systems according to Vx = TXX' VXI. Solution of this problem using the standard Eulerian angle techniques is in general tedious and circuitous. A straightforward, simple, and efficient solution for the transformation matrix is...

We deal with matrix transformations preserving the starshape of sequences. The main result gives the necessary and sufficient conditions for a lower triangular matrix A to preserve the starshape of sequences. Also, we discuss the nature of the mappings of starshaped sequences by some classical matrices. 2000 Mathematics Subject Classification. 40C05, 40D05, 40G05.

Some near-regular mechanical systems involve global deviations from their corresponding regular system. Despite extensive research on vibration analysis (eigensolution) of regular and local near-regular mechanical systems, the literature on vibration analysis of global near-regular mechanical systems is scant. In this paper, a method for vibration analysis of such systems was developed using Kr...

There are many programming situations where it would be convenient to conceal the meaning of code, or the meaning of certain variables. This can be achieved through program transformations which are grouped under the term obfuscation. Obfuscation is one of a number of techniques that can be employed to protect sensitive areas of code. This paper presents obfuscation methods for the purpose of c...

Exploiting locality is critical to achieving good performance. For regular programs, which operate on dense arrays and matrices, techniques such as loop interchange and tiling have long been known to improve locality and deliver improved performance. However, there has been relatively little work investigating similar locality-improving transformations for irregular programs that operate on tre...

A new scheme has been devised to represent viruses and other biological assemblies with regular noncrystallographic symmetry in the Protein Data Bank (PDB). The scheme describes existing and anticipated PDB entries of this type using generalized descriptions of deposited and experimental coordinate frames, symmetry and frame transformations. A simplified notation has been adopted to express the...

We consider the spherical limit of multi-matrix models on regular target graphs, for instance single or multiple Potts models, or lattices of arbitrary dimension. We show, to all orders in the low temperature expansion, that when the degree of the target graph ∆ → ∞, the free energy becomes independent of the target graph, up to simple transformations of the matter coupling constant. Furthermor...

Based on the upper-triangular Hessenberg forms for descriptor linear systems and a method for right coprime factorization of descriptor linear systems using matrix elementary transformations, a simple, neat and numerically stable iterative formula for right coprime factorization of a regular singleinput descriptor linear system is proposed. This iterative formula gives directly the coefficients...

In this paper, we consider the regularization problem for the linear time-varying discrete-time periodic descriptor systems by derivative and proportional state feedback controls. Sufficient conditions are given under which derivative and proportional state feedback controls can be constructed so that the periodic closed-loop systems are regular and of index at most one. The construction proced...