Computer Science Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2756
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Item On Numerical Analysis in Residue Number Systems(1964) Lindamood, George Edward; Rheinboldt, Werner C.; Computer Science Center; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Recent attempts to utilize residue number systems in digital computers have raised numerous questions about adapting the techniques of numerical analysis to residue number systems. Among these questions are the fundamental problems of how to compare the magnitudes of two numbers, how to detect additive and multiplicative overflow, and how to divide in residue number systems. These three problems are treated in separate chapters of this thesis and methods are developed therein whereby magnitude comparison, overflow detection, and division can be performed in residue number systems. In an additional chapter, the division method is extended to provide an algorithm for the direct approximation of square roots in residue number systems. Numerous examples are provided illustrating the nature of the problems considered and showing the use of the solutions presented in practical computations. In a final chapter are presented the results of extensive trial calculations for which a conventional digital computer was programmed to simulate the use of the division and square root algorithms in approximating quotients and square roots in residue number systems. These results indicate that, in practice, these division and square root algorithms usually converge to the quotient or square root somewhat faster than is suggested by the theory.Item Restructuring Textual Information for Online Retrieval(1985) Koved, Lawrence; Shneiderman, Ben; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Two experiments were conducted to evaluate two styles of online documents. The first experiment compared paper manuals to online manuals using two different database structuring techniques - a sequential (linear) structure and a tree structure. People using the paper manuals were faster at solving problems than the people using the computer manuals. No differences were found between the linear and tree structures, or in accuracy of problem solutions. In a subjective evaluation of user preferences, the computer manuals were rated as better and more organized than the paper manuals. The second experiment compared two methods of retrieving online information that allowed the reader to specify the attributes needed to guide the information retrieval process. The first manual recorded the attributes entered by the reader via menus, and material in the manuals not relevant to the current search was pruned from the search space. The second manual did not record the menu selections, and the readers repeatedly entered the attributes several times in order to complete the task. The manual that recorded the attributes allowed the readers to work over twice as fast and was pref erred over the other manual. A theoretical foundation is presented for the underlying online documentation used in the experiments. The user's traversal through the database is presented as a graph search process, using a production system. The results of the experiments and their theoretical foundations are evaluated in terms of the impact they might have on future online document storage and retrieval systems.