Scientific Programming - Volume 11, issue 4

Authors: Bischof, Christian H. | Bücker, H. Martin | Lang, Bruno | Rasch, Arno

Article Type: Research Article

Abstract: Numerical simulation is a powerful tool in science and engineering, and it is also used for optimizing the design of products and experiments rather than only for reproducing the behavior of scientific and engineering systems. In order to reduce the number of simulation runs, the traditional "trial and error" approach for finding near-to-optimum design parameters is more and more replaced with efficient numerical optimization algorithms. Done by hand, the coupling of simulation and optimization software is …tedious and error-prone. In this note we introduce a software environment called EFCOSS (Environment For Combining Optimization and Simulation Software) that facilitates and speeds up this task by doing much of the required work automatically. Our framework includes support for automatic differentiation providing the derivatives required by many optimization algorithms. We describe the process of integrating the widely used computational fluid dynamics package FLUENT and a MINPACK-1 least squares optimizer into EFCOSS and follow a sample session solving a data assimilation problem. Show more

Citation: Scientific Programming, vol. 11, no. 4, pp. 263-272, 2003

Authors: Landry, Walter

Article Type: Research Article

Abstract: Template methods have opened up a new way of building C++ libraries. These methods allow the libraries to combine the seemingly contradictory qualities of ease of use and uncompromising efficiency. However, libraries that use these methods are notoriously difficult to develop. This article examines the benefits reaped and the difficulties encountered in using these methods to create a friendly, high performance, tensor library. We find that template methods mostly deliver on this promise, though requiring moderate …compromises in usability and efficiency. Show more

Citation: Scientific Programming, vol. 11, no. 4, pp. 273-290, 2003

Authors: Schupp, Sibylle

Article Type: Research Article

Abstract: While modern software engineering, with good reason, tries to establish the idea of reusability and the principles of parameterization and loosely coupled components even for the design of performance-critical software, Fast Fourier Transforms (FFTs) tend to be monolithic and of a very low degree of parameterization. The data structures to hold the input and output data, the element type of these data, the algorithm for computing the so-called twiddle factors, the storage model for a given …set of twiddle factors, all are unchangeably defined in the so-called butterfly, restricting its reuse almost entirely. This paper shows a way to a component-based FFT by designing a parameterized butterfly. Based on the technique of lifting, this parameterization includes algorithmic and implementation issues without violating the complexity guarantees of an FFT. The paper demonstrates the lifting process for the Gentleman-Sande butterfly, i.e., the butterfly that underlies the large class of decimation-in-frequency (DIF) FFTs, shows the resulting components and summarizes the implementation of a component-based, generic DIF library in C++. Show more

Citation: Scientific Programming, vol. 11, no. 4, pp. 291-307, 2003

Authors: Gregor, Douglas | Schupp, Sibylle | Musser, David R.

Article Type: Research Article

Abstract: We apply the notion of design patterns to optimizations performed by designers of software libraries, focusing especially on object-oriented numerical libraries. We formalize three design patterns that we have abstracted from many existing libraries and discuss the role of these formalizations as a tool for guiding compiler optimizers. These optimizers operate at a very high level that would otherwise be left unoptimized by traditional optimizers. Finally, we discuss the implementation of a design pattern-based compiler …optimizer for C++ abstract data types. Show more

Citation: Scientific Programming, vol. 11, no. 4, pp. 309-320, 2003

Authors: Cole, Martin J. | Parker, Steven G.

Article Type: Research Article

Abstract: Generic programming using the C++ template facility has been a successful method for creating high-performance, yet general algorithms for scientific computing and visualization. However, adding template code tends to require more template code in surrounding structures and algorithms to maintain generality. Compiling all possible expansions of these templates can lead to massive template bloat. Furthermore, compile-time binding of templates requires that all possible permutations be known at compile time, limiting the runtime …extensibility of the generic code. We present a method for deferring the compilation of these templates until an exact type is needed. This dynamic compilation mechanism will produce the minimum amount of compiled code needed for a particular application, while maintaining the generality and performance that templates innately provide. Through a small amount of supporting code within each templated class, the proper templated code can be generated at runtime without modifying the compiler. We describe the implementation of this goal within the SCIRun dataflow system. SCIRun is freely available online for research purposes. Show more

Citation: Scientific Programming, vol. 11, no. 4, pp. 321-327, 2003