https://ir.unisa.ac.za/handle/10500/24450 Tue, 12 May 2026 22:42:13 GMT 2026-05-12T22:42:13Z https://ir.unisa.ac.za/handle/10500/24820 An overview of the Internet services available in South Africa Radovanovic, A; Venter, DM Steenkamp, A.L. South African networking history started in the mid 1980's. Within less than ten years, the country became the 15-th fastest growing network within the lnternet community. Today, the South African network offers a variety of services on more than 20,000 Internet servers. The new information retrieval tools, as well as the new networking technologies, has pushed research towards a South African version of the "Information Superhighway". Sun, 01 Jan 1995 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/24820 1995-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/24819 Rank-one update of Cholesky factorization Ntlatlapa, N Steenkamp, A.L. Symmetric positive definite matrices appear in most methods for Unconstrained Optimization. The method widely adopted for factoring these matrices is Cholesky Factorization. Furthermore, in Quassi-Newton methods for unconstrained optimization these matrices are continually updated and factorized. Here we consider factoring an n x n symmetric positive definite matrix of the form: A' = A + CXZZT , where A is symmetric positive definite, a is a scalar and z is a vector of length n. We assume that A has already been factorized by Cholesky factorization. The adopted methods are due to Gill et. al. [GGS75, GM72]. Sun, 01 Jan 1995 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/24819 1995-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/24818 The design of a 2D non-linear filter for digital image processing Cloete, E Steenkamp, A.L. A 1 D non-linear filter which is based on 'max-min' selectors is extended for use in 2 0 applications. The objective of this research is to remove impulsive noise without unduly changing original, valid data. Some examples are presented to indicate the use of this new filter as a pre-filter for detecting dense regions of images. Sun, 01 Jan 1995 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/24818 1995-01-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/24817 Higraphs: an overview of theory and application Hillebrand, G Steenkamp, A.L. This paper presents an overview of the established concepts of David Harel' s higraphs, to increase their visibility. Higraphs are a union of extended graph and extended set theory which allows the understandable definition of complex semantics, having a powerful intuitive cognitive nature. Viewing 'the big picture' is cited as an example of this understandability. A number of other applications of higraphs are given. Some novel applications are suggested, including the use of higraphs in analyzing business processes, graphical user interface specification, graph domain specification and executable graphs, A proposition is made that process graphs and data-entity state-transition higraphs are duals. Finally, a case is made for 'informal' higraphs in group communications. Sun, 01 Jan 1995 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/24817 1995-01-01T00:00:00Z