Unit one is intrusive.

The SI brochure's treatment of quantities that it regards as dimensionless, with the associated unit one, requires certain physical quantities to be regarded as simply numbers. The resulting formal system erases the nature of these quantities and excludes them from important benefits that quantity calculus provides over numerical value calculations, namely, that accidental confusion of different units and different kinds of quantities is sometimes prevented. I propose a better treatment that entails removing from the SI brochure those prescriptions that conflict with common practices in the treatment of dimensionless quantities, especially the definition and use of non-SI dimensionless units that are distinguished by kind.

A system of quantities from software metrology.

International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) 80000, the International System of Quantities, collects and organizes the most important physical quantities into a coherent system of quantities whose foundation for measurements is the International System of Units (SI). This short communication outlines a report that, in a similar fashion, collects and organizes the most important quantities used in measurements performed on software artifacts, focusing on software as a product rather than its development process.

Architecture for software-assisted quantity calculus.

A quantity value, such as 5 kg, consists of a number and a reference (often an International System of Units (SI) unit) that together express the magnitude of a quantity. Many software libraries, packages, and ontologies that implement "quantities and units " functions are available. Although all of them begin with SI and associated practices, they differ in how they address issues such as ad hoc counting units, ratios of two quantities of the same kind, and uncertainty. This short article describes an architecture that addresses the complete set of functions in a simple and consistent fashion. Its goal is to encourage more convergent thinking about the functions and the underlying concepts so that the many disparate implementations, present and future, will become more consistent with one another.

Redressing grievances with the treatment of dimensionless quantities in SI.

The International System of Units (SI) and its associated methods adhere to a design principle in which all kinds of quantities are described in terms of a standard set of dimensions. It is a corollary of that principle that quantities having no extent in any of those dimensions ("dimensionless quantities") will not be distinguishable as different kinds through dimensional analysis alone, and the formality of quantity calculus will be of no help in preventing mistakes where different kinds of dimensionless quantities are confused. This corollary has led to controversies involving abuse of the unit hertz and elimination of radians and steradians as being equivalent to the number 1. In addition, official rejection of the use of so-called counting units in conjunction with accepted units has been repeatedly criticized and is often ignored. The proposed resolution is to extend quantity calculus to discern different kinds of dimensionless quantities as well as it currently discerns different kinds of dimensional quantities. The extended system provides a formal interpretation of commonly-used workarounds in terms that are compatible with SI. Should the extended quantity calculus become accepted by consensus in the future, a guide to its use would expand the set of references provided by the Joint Committee for Guides in Metrology (JCGM), which currently lacks a definitive reference on quantity calculus.

A Case Study of Performance Degradation Attributable to Run-Time Bounds Checks on C++ Vector Access.

Programmers routinely omit run-time safety checks from applications because they assume that these safety checks would degrade performance. The simplest example is the use of arrays or array-like data structures that do not enforce the constraint that indices must be within bounds. This report documents an attempt to measure the performance penalty incurred by two different implementations of bounds-checking in C and C++ using a simple benchmark and a desktop PC with a modern superscalar CPU. The benchmark consisted of a loop that wrote to array elements in sequential order. With this configuration, relative to the best performance observed for any access method in C or C++, mean degradation of only (0.881 ± 0.009) % was measured for a standard bounds-checking access method in C++. This case study showed the need for further work to develop and refine measurement methods and to perform more comparisons of this type. Comparisons across different use cases, configurations, programming languages, and environments are needed to determine under what circumstances (if any) the performance advantage of unchecked access is actually sufficient to outweigh the negative consequences for security and software quality.

A Logical Model of Conceptual Integrity in Data Integration.

Conceptual integrity is required for the result of data integration to be cohesive and sensible. Compromised conceptual integrity results in "semantic faults," which are commonly blamed for latent integration bugs. A logical model of conceptual integrity in data integration and a simple example application are presented. Unlike constructive models that attempt to prevent semantic faults, this model allows both correct and incorrect integrations to be described. Imperfect legacy systems can therefore be modeled, allowing a more formal analysis of their flaws and the possible remedies.