Abstract. Geometric predicates are used in many GIS algorithms, such as the construction of Delaunay Triangulations for Triangulated Irregular Networks (TIN) or geospatial predicates. With floating-point arithmetic, these computations can incur roundoff errors that may lead to incorrect results and inconsistencies, causing fail. This issue has been addressed using a combination exact arithmetic...

We develop the theory of interstellar scintillation as caused by an irregular plasma having a power-law spatial density spectrum with a spectral exponent of β = 4 corresponding to a medium with abrupt changes in its density. An “outer scale” is included in the model representing the typical scale over which the density of the medium remains uniform. Such a spectrum could be used to model plasma...

although treated properly for epilepsy, a number of epileptic children have intractable seizures and about 5-10 per cent of them do not respond to anti -epileptic drugs. in the years 1986-1996 about 10,000 epileptic patients were treated in the children's medical center in tehran. a retrospective study of their medical records revealed that 41 of them had intractable seizures. i of these 4...

Mass spring systems (MSS) are frequently used to simulate deformable objects because of their conceptual simplicity and computational speed. Unfortunately, the model parameters (spring coefficients, masses) are not related to material constitutive laws in an obvious way. In our earlier work we proposed a method, which can be used to relate the parameters of the MSS to constitutive models, often...

We present a volumetric method that can e ciently create triangular meshes from 3-D geometric data. This data can be presented in the form of images, pro les or unordered points. The mesh model can be created at di erent resolutions and can also be closed to make a true volumetric model.

Several “distances” between the spectra of two regular matrix pencils are discussed and compared. The relations obtained enable us to estimate upper bounds on one “distance” via known upper bounds on others. We also give some perturbation bounds and then show how to apply the relations obtained in this note.

A multilinear approach based on Grassmann representatives and matrix compounds is presented for the identification of reducing pairs of subspaces that are common to two or more matrices. Similar methods are employed to characterize the deflating pairs of subspaces for a regular matrix pencil A+ sB, namely, pairs of subspaces (L,M) such that AL ⊆ M and BL ⊆ M.

PURPOSE To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction. SETTING Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. METHODS Three groups of patients with low myopia correction (spectacles, soft contact lens, and Intacs) and 4 groups with high myopia correction (spectacles, rigid c...

Let f : Cn → C be a polynomial map. The polynomial describes a family of complex affine hypersurfaces f−1(c), c ∈ C. The family is locally trivial, so the hypersurfaces have constant topology, except at finitely many irregular fibers f−1(c) whose topology may differ from the generic or regular fiber of f . We would like to give a full description of the topology of this family in terms of easil...