Flowchart

Abstract: A direct-manipulation user interface presents a set of visual representations on a display and a repertoire of manipulations that can be performed on any of them. Such representations might include screen buttons, scroll bars, spreadsheet cells, or flowchart boxes. Interaction techniques of this kind were first seen in interactive graphics systems; they are now proving effective in user interfaces for applications that are not inherently graphical. Although they are often easy to learn and use, these interfaces are also typically difficult to specify and program clearly.Examination of direct-manipulation interfaces reveals that they have a coroutine-like structure and, despite their surface appearance, a peculiar, highly moded dialogue. This paper introduces a specification technique for direct-manipulation interfaces based on these observations. In it, each locus of dialogue is described as a separate object with a single-thread state diagram, which can be suspended and resumed, but retains state. The objects are then combined to define the overall user interface as a set of coroutines, rather than inappropriately as a single highly regular state transition diagram. An inheritance mechanism for the interaction objects is provided to avoid repetitiveness in the specifications. A prototype implementation of a user-interface management system based on this approach is described, and example specifications are given.

Abstract: One of the practical methods commonly used to detect the presence of errors in a computer program is to test it for a set of test cases. The probability of discovering errors through testing can be increased by selecting test cases in such a way that each and every branch in the flowchart will be traversed at least once during the test. This tutorial describes the problems involved and the methods that can be used to satisfy the test requirement.

Abstract: An implementation of Tarj an's algorithm for symmetrically permuting a given matrix to block tmangular form is described. The discussion includes a flowchart of the algorithm, a complexity analysis, and a comparison with the earlier widely used algorithm of Sargent and Westerberg. T~ming results are presented from several experiments using the code developed by the authors.

Abstract: objects have been devdloped. The diagrams, flowcharts, and other iconic representations we have long employed to communicate with other people can now be used directly to describe algorithms to computers. With the availability of graphics-based, personal workstations, these visual modes can eliminate the need to convert algorithms to the linear strings of symbols traditionally required by most computers. Linear, symbolic computer languages have been studied and refined extensively over the past 30 years, but computer language designers now face a new challenge: to provide convenient and natural visual programming lan-