Debugging methods in recursive structured FORTRAN

A version of structured FORTRAN named STAR is introduced. STAR allows recursive subroutines. Implementation problems such as parameter passing by value and local variable stacking are discussed. The major difficulty in the preprocessor approach is debugging. We claim that execution profiles are strong debugging aids, and demonstrate how to debug a STAR program at source language level with the clue in the profiles plus assertion statements. We make use of a quicksort program as an example.     

Optimization of structured programs

The class of programs which do not contain goto statements has a structure which lends itself to optimization by an optimizer that is fast, efficient and relatively easy to program. The design of such an optimizer is described, along with some of the results obtained using this optimizer—one such result being that very little code optimization is achieved. The conjecture is made that this is true because gotoless programming languages lend themselves to more compact and concise object code at the source language level.     

Comorphisms of structured institutions

In this paper we formalise the intuition of encoding an institution of structured specifications into another one by extending the concept of institution comorphism to the abstract framework of structured institutions. This allows us to define a category of comorphisms of structured institutions, and supports in this way the development of heterogeneous specification languages in which the actual structuring mechanisms may vary, in addition to the base logical systems. We consider a number of properties with practical relevance for the comorphisms between base institutions and discuss their implications in the structured setting.     

Parametric identification of structured nonlinear systems

In this paper, identification of structured nonlinear systems is considered. Using linear fractional transformations (LFT), the a priori information regarding the structural interconnection is systematically exploited. A parametric approach to the identification problem is investigated, where it is assumed that the linear part of the interconnection is given and the input to the nonlinear part is measurable. An algorithm for the identification of the nonlinear part is proposed. The uniqueness properties of the estimate provided by the algorithm are examined. It is shown that the estimate converges asymptotically to its true value under a certain persistence of excitation condition. Two simulated examples and a real-data example are presented to show the effectiveness of the proposed algorithm.     

A language-independent system to aid the development of structured programs

The GLIDE system is an effectively language-independent aid of modest proportions for developing programs by stepwise refinement. The basis of the system is a suitable program file environment The system has been implemented on the Imperial College Computer Centre Control Data machine and is currently available for the development of programs written in PASCAL, ALGOL, FORTRAN, SIMULA and JCL (Job Control Language). The program itself is written in PASCAL The facilities obtained within the scope and limitations of the system conception suggest that this type of system could be given further attention.     

A detailed comparative analysis of all practical algorithms to compute lower bounds on the structured singular value

μ analysis is one of the most efficient techniques to evaluate the stability margins and the performance levels of linear time-invariant systems in the presence of structured time-invariant uncertainties. The exact computation of the structured singular value μ is known to be NP hard in the general case, but several methods have been developed in the last 30 years to compute accurate and reliable bounds. In this paper, all existing μ lower bound algorithms are reviewed and the most relevant ones are evaluated on a wide set of real-world benchmarks, corresponding to various fields of application, system dimensions and structures of the uncertainties. The results are thoroughly analyzed and simple improvements to the existing algorithms are proposed to approach the exact value of μ with a reasonable computation cost. Conclusions show that non-conservative values can be obtained in almost all cases. A brief extension to skew-μ analysis confirms the good results obtained in the classical μ case.     

Generating strictly non-self-overlapping structured quadrilateral grids

In this paper, we present a BPM (Bézier patch mapping) algorithm which generates a strictly non-self-overlapping structured quadrilateral grid in a given four-sided planar region. Given four pieces of polynomial curves which enclose a simple region in the plane, the algorithm first constructs a Bézier patch which interpolates the four curves (as its four boundary curves), while the inner control points of its control grid remain unknown. In this paper, we show that, for the bijective condition to be satisfied, it is sufficient that the interior points satisfy a set of quadratic inequality equations. Exploiting this key result, we formulate the mapping algorithm as an optimization problem where the constraints are the bijective condition of the Bézier patch mapping (BPM), and the objective is to find out the best from all of the non-self-overlapping grids. Thus, commercial optimization solvers can be used to find the bijective mapping. If a solution to the optimization problems exists, then so does a solution to the mapping problem, and vice-versa. The BPM method is simple and intuitive, and some examples presented in this paper demonstrate its effectiveness.     

Presenting software engineering results using structured abstracts: a randomised experiment

When conducting a systematic literature review, researchers usually determine the relevance of primary studies on the basis of the title and abstract. However, experience indicates that the abstracts for many software engineering papers are of too poor a quality to be used for this purpose. A solution adopted in other domains is to employ structured abstracts to improve the quality of information provided. This study consists of a formal experiment to investigate whether structured abstracts are more complete and easier to understand than non-structured abstracts for papers that describe software engineering experiments. We constructed structured versions of the abstracts for a random selection of 25 papers describing software engineering experiments. The 64 participants were each presented with one abstract in its original unstructured form and one in a structured form, and for each one were asked to assess its clarity (measured on a scale of 1 to 10) and completeness (measured with a questionnaire that used 18 items). Based on a regression analysis that adjusted for participant, abstract, type of abstract seen first, knowledge of structured abstracts, software engineering role, and preference for conventional or structured abstracts, the use of structured abstracts increased the completeness score by 6.65 (SE 0.37, p < 0.001) and the clarity score by 2.98 (SE 0.23, p < 0.001). 57 participants reported their preferences regarding structured abstracts: 13 (23%) had no preference; 40 (70%) preferred structured abstracts; four preferred conventional abstracts. Many conventional software engineering abstracts omit important information. Our study is consistent with studies from other disciplines and confirms that structured abstracts can improve both information content and readability. Although care must be taken to develop appropriate structures for different types of article, we recommend that Software Engineering journals and conferences adopt structured abstracts.

A Coalgebraic presentation of structured transition systems

This paper relates labelled transition systems and coalgebras with the motivation of comparing and combining their complementary contributions to the theory of concurrent systems. The well-known mismatch between these two notions concerning the morphisms is resolved by extending the coalgebraic framework by lax cohomomorphisms.

Enriching both labelled transition systems and coalgebras with algebraic structure for an algebraic specification, the correspondence is lost again. This motivates the introduction of lax coalgebras, where the coalgebra structure is given by a lax homomorphism. The resulting category of lax coalgebras and lax cohomomorphisms for a suitable endofunctor is shown to be isomorphic to the category of structured transition systems, where both states and transitions form algebras.

The framework is also presented on a more abstract categorical level using monads and comonads, extending the bialgebraic approach introduced by Turi and Plotkin.     

基于负载平衡的搜索算法研究

本文针对语义拆分的平衡算法提出了基于请求者反馈的搜索算法,然后对算法的搜索长度进行了分析,通过限定负载平衡时语义类移动的最大次数和聚类中节点的数目可以控制搜索服务的最大时间延时。     

Effects of structured programming on PL/I programmers

A PL/I system has been implemented which automatically collects and saves information on every program compiled and executed. This note describes some of the analysis that has been performed on approximately 9,000 of these collected programs.     

Inductive manifold learning using structured support vector machine

Most manifold learning techniques are used to transform high-dimensional data sets into low-dimensional space. In the use of such techniques, after unseen data samples are added to the data set, retraining is usually necessary. However, retraining is a time-consuming process and no guarantee of the transformation into the exactly same coordinates, thus presenting a barrier to the application of manifold learning as a preprocessing step in predictive modeling. To solve this problem, learning a mapping from high-dimensional representations to low-dimensional coordinates is proposed via structured support vector machine. After training a mapping, low-dimensional representations of unobserved data samples can be easily predicted. Experiments on several datasets show that the proposed method outperforms the existing out-of-sample extension methods.     

Addressing spatiotemporal and computational heterogeneity in structured adaptive mesh refinement

Structured adaptive mesh refinement (SAMR) techniques can provide accurate and cost- effective solutions to realistic scientific and engineering simulations modeling complex physical phenomena. However, the adaptive nature and inherent space–time heterogeneity of SAMR applications result in significant runtime management challenges. Moreover, certain SAMR applications involving reactive flows exhibit pointwise varying workloads and cannot be addressed by traditional parallelization approaches, which assume homogeneous loads. This paper presents hierarchical partitioning, bin-packing based load balancing, and Dispatch structured partitioning strategies to manage the spatiotemporal and computational heterogeneity in SAMR applications. Experimental evaluation of these schemes using 3-D Richtmyer–Meshkov compressible turbulence and 2-D reactive-diffusion kernels demonstrates the improvement in overall performance.     

Piecewise training for structured prediction

A drawback of structured prediction methods is that parameter estimation requires repeated inference, which is intractable for general structures. In this paper, we present an approximate training algorithm called piecewise training (PW) that divides the factors into tractable subgraphs, which we call pieces, that are trained independently. Piecewise training can be interpreted as approximating the exact likelihood using belief propagation, and different ways of making this interpretation yield different insights into the method. We also present an extension to piecewise training, called piecewise pseudolikelihood (PWPL), designed for when variables have large cardinality. On several real-world natural language processing tasks, piecewise training performs superior to Besag’s pseudolikelihood and sometimes comparably to exact maximum likelihood. In addition, PWPL performs similarly to PW and superior to standard pseudolikelihood, but is five to ten times more computationally efficient than batch maximum likelihood training.     

MOAB-SD: integrated structured and unstructured mesh representation

Structured and semi-structured (a.k.a. swept or extruded) hexahedral meshes are used in many types of engineering analysis. In finite element analysis, regions of structured and semi-structured mesh are often connected in an unstructured manner, preventing the use of a globally consistent parametric space to represent these meshes. This paper describes a method for mapping between the parametric spaces of such regions, and methods for representing these regions and interfaces between them. Using these methods, a 57% reduction in mesh storage cost is demonstrated, without loss of any information. These methods have been implemented in the MOAB mesh database component, which provides access to these meshes from both structured and unstructured functions. The total cost for representing structured mesh in MOAB is less than 25 MB per million elements using double-precision vertex coordinates; this is only slightly larger than the space required to store vertex coordinates alone.Sandia is a multiprogram laboratory operated by Sandia corporation, a Lockheed Martin company, for the United States department of energy under contract DE-AC04-94AL85000. This work was performed under the auspices of the U.S. Department of Energy, Office of Advanced Scientific Computing, SciDAL program.     

Observability analysis for structured bilinear systems: A graph-theoretic approach

This paper is devoted to the generic observability analysis for structured bilinear systems using a graph-theoretic approach. On the basis of a digraph representation, we express in graphic terms the necessary and sufficient conditions for the generic observability of structured bilinear systems. These conditions have an intuitive interpretation and are easy to check by hand for small systems and by means of well-known combinatorial techniques for large-scale systems.