Browsing by Author "Colijn, A.W."

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    AN ALGORITHM FOR BALANCING BINARY TREES
    (1981-08-01) Colijn, A.W.
    An algorithm is presented for balancing binary trees; the algorithm re-structures in place any tree of arbitrary structure, to produce a tree with the property that the numbers of left and right descendants of any node differ by at most one. The algorithm is convenient to use, and it is fast; the time required to balance a tree varies linearly with the number of nodes. Experimental results and variations of the basic algorithm are discussed.
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    CSSL-IV ON THE CYBER 205 A STUDY IN SUITABILITY
    (1988-01-01) Colijn, A.W.; Ariel, P.D.
    A study is made of the suitability of the continuous systems simulation language CSSL-IV on the Cyber 205. In an earlier paper by the authors, models characterized by parabolic and hyperbolic partial differential equations were simulated using CSSL-IV. In the present paper, the model of Faraday generator, which can be described by means of a pair of elliptical partial differential equations in velocity and induced magnetic field, is simulated. The equal velocity and current lines contours have been obtained for values of Hartmann numbers up to 20. No acceptable solutions could be obtained for larger values of Hartmann numbers. In an attempt to explain the source of inaccuracy, a mathematical analysis of the solution of Poisson's equation, using CSSL-IV, has been presented. It is demonstrated that a decrease in the value of the descretization interval size actually leads to exponentially growing solutions. This fact, somewhat, limits the suitability of CSSL-IV on the Cyber 205 for the simulation of models characterized by elliptical partial differential equations.
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    A NOTE ON THE MULTICS COMMAND LANGUAGE
    (1980-12-01) Colijn, A.W.
    Some aspects of the Multics operating system are critically examined. In particular, the properties of the command and language are noted as allowing considerable general purpose programming power. The strength and weaknesses are discussed and a quantitative evaluation of speed is attempted based on a comparison of programming the "Towers of Hanoi" and Ackermann's function in both Multics command language and pll. The programs also serve to exemplify the use of the command language.
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    A RESULT FOR THE EXTENDED SCHOOL TIME-TABLING PROBLEM WITH PRE-ASSIGNMENTS
    (1981-03-01) Colijn, A.W.
    Necessary and sufficient conditions are presented for the existence of a solution to the extended school time-tabling problem, in which each class (or year-group) and each teacher (or teaching department) is available more than once during each period, and in which pre-assignments may occur. An algorithm for constructing time-tables follows naturally from the proof of the result.(1)