Software Engineering and Programming Languages
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Applications of differential equations in general problem solving
A large class of problems leading to digital computer processing can be formulated in terms of the numerical solution of systems of ordinary differential equations. Powerful methods are in existence for the solution of such systems. A good general purpose routine for the solution of such systems furnishes a powerful tool for processing many problems. This is true from the point of view of ease of programming, ease of debugging, and minimization of computer time. A number of examples are discussed in detail.
On reversible subroutines and computers that run backwards
A computer design is described which permits subroutines to be executed backward as well as forward, either with their instructions unchanged or replaced with conjugate instructions. It is shown that using this concept a number of new subroutine types can be developed with rather unusual properties. Since these properties are analogous to certain matrix operations, a arallel nomenclature is suggested for their classification.
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UPLIFTS—University of Pittsburgh linear file tandem system
A series of computer programs has been developed and is now operational for processing the National Aeronautics and Space Administration linear file system on an IBM 1401-7090 combined data processing system. The programs are noteworthy in that they create fixed length logical records and fixed length blocks from variable length source data, and format the output for optimization of processing on the IBM 7090 system. The programs are completely self-checking and test for both validity and accuracy of the input materials as provided by the National Aeronautics and Space Administration.
Negative and zero subscripts in Fortran II programming for the IBM 1620
The requirement that subscripts be unsigned integers creates some inconvenience in FORTRAN programming for summarization of completed questionnaires in which the responses may be scaled beginning at zero.
Some experiments in algebraic manipulation by computer
A set of subroutines to allow algebraic manipulations on the IBM 7094 computer has been written using a List Processor, SLIP.
A series of four problems of increasing difficulty were solved using these routines.
A method for storing strings is described which uses blocks of indefinite size, and is therefore completely dynamic. Its relation to similar schemes is discussed.
Symbolic derivatives without list processing, subroutines, or recursion
A routine has been developed which computes and prints out the symbolic derivative of an absolutely continuous elementary function of one or several variables. No use is made of list processing languages. The chain rule is applied and the result is edited to produce results as elegant and efficient as those obtained by hand computation. A subset may be imbedded in a formula translator to introduce a differentiation operator into an “algebraic” programming language.
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