Using a specific solver for circulant matrices can reduce the cost of computing the scattering from a discrete rotational symmetric object by up to several orders of magnitude. In this paper, a solver is developed for symmetric objects with a nonsymmetrical part (such as an antenna on a body of revolution). This solver has been implemented in a finite-element code based upon a hybrid formulation. The hybrid formulation combines integral equations and partial differential equations; it can handle inhomogeneous anisotropic objects of arbitrary shape. Results on inhomogeneous objects with defects are shown. The solver can also be used to perform a parametric study of the defects.Index Terms-Boundary integral equations, electromagnetic scattering, finite-element method.

Among the programming models for parallel and distributed computing, one can identify two important families. The programming models adapted to data-parallelism, where a set of coordinated processes perform a computation by splitting the input data; and coordination languages able to express complex coordination patterns and rich interactions between processing entities. This article takes two successful programming models belonging to the two categories and puts them together into an effective programming model. More precisely, we investigate the use of active objects to coordinate BSP processes. We choose two paradigms that both enforce the absence of data-races, one of the major sources of error in parallel programming. This article explains why we believe such a model is interesting and provides a formal semantics integrating the notions of the two programming paradigms in a coherent and effective manner.

This paper defines distributed futures, a construct that provides at the same time a data container similar to a distributed vector, and a single synchronization entity that behaves similarly to a standard future. This simple construct makes it easy to program a composition, in a task-parallel way, of several massively data-parallel tasks. The approach is implemented and evaluated in the context of a bulk synchronous parallel (BSP) active object framework. CCS CONCEPTS• Software and its engineering → Parallel programming languages; Concurrent programming structures.

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