682 research outputs found

    Interval-based simulation of ZĂ©lus IVPs using DynIbex

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    Modeling continuous-time dynamical systems is a complex task. Fortunately some dedicated programming languages exist to ease this work. ZĂ©lus is one such language that generates a simulation executable which can be used to study the behavior of the modeled system. However, such simulations cannot handle uncertainties on some parameters of the system. This makes it necessary to run multiple simulations to check that the system fulfills particular requirements (safety for instance) for all the values in the uncertainty ranges. Interval-based guaranteed integration methods provide a solution to this problem. The DynIbex library provides such methods but it requires a manual encoding of the system in a general purpose programming language (C++). This article presents an extension of the ZĂ©lus compiler to generate interval-based guaranteed simulations of IVPs using DynIbex. This extension is conservative since it does not break the existing compilation workflow

    Expression Acceleration: Seamless Parallelization of Typed High-Level Languages

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    Efficient parallelization of algorithms on general-purpose GPUs is today essential in many areas. However, it is a non-trivial task for software engineers to utilize GPUs to improve the performance of high-level programs in general. Although many domain-specific approaches are available for GPU acceleration, it is difficult to accelerate existing high-level programs without rewriting parts of the programs using low-level GPU code. In this paper, we propose a different approach, where expressions are marked for acceleration, and the compiler automatically infers which code needs to be accelerated. We call this approach expression acceleration. We design a compiler pipeline for the approach and show how to handle several challenges, including expression extraction, well-formedness, and compiling using multiple backends. The approach is designed and implemented within a statically-typed functional intermediate language and evaluated using three distinct non-trivial case studies

    A Synchronous Look at the Simulink Standard Library

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    International audienceHybrid systems modelers like Simulink come with a rich collection of discrete-time and continuous-time blocks. Most blocks are not defined in terms of more elementary ones—and some cannot be—but are instead written in imperative code and explained informally in a reference manual. This raises the question of defining a minimal set of orthogonal programming constructs such that most blocks can be programmed directly and thereby given a specification that is mathematically precise, and whose compiled version performs comparably to handwritten code. In this paper, we show that a fairly large set of blocks of a standard library like the one provided by Simulink can be programmed in a precise, purely functional language using stream equations, hierarchical automata, Ordinary Differential Equations (ODEs), and deterministic synchronous parallel composition. Some blocks cannot be expressed in our setting as they mix discrete-time and continuous-time signals in unprincipled ways that are statically forbidden by the type checker. The experiment is conducted in Zélus, a synchronous language that conservatively extends Lustre with ODEs to program systems that mix discrete-time and continuous-time signals

    Acta Cybernetica : Volume 25. Number 1.

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    Type-driven automated program transformations and cost modelling for optimising streaming programs on FPGAs

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    In this paper we present a novel approach to program optimisation based on compiler-based type-driven program transformations and a fast and accurate cost/performance model for the target architecture. We target streaming programs for the problem domain of scientific computing, such as numerical weather prediction. We present our theoretical framework for type-driven program transformation, our target high-level language and intermediate representation languages and the cost model and demonstrate the effectiveness of our approach by comparison with a commercial toolchain

    Differential-Algebraic Equations and Beyond: From Smooth to Nonsmooth Constrained Dynamical Systems

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    The present article presents a summarizing view at differential-algebraic equations (DAEs) and analyzes how new application fields and corresponding mathematical models lead to innovations both in theory and in numerical analysis for this problem class. Recent numerical methods for nonsmooth dynamical systems subject to unilateral contact and friction illustrate the topicality of this development.Comment: Preprint of Book Chapte
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