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Manuscript Title: OLYMPUS - a standard control and utility package for initial-value Fortran programs.
Authors: J.P. Christiansen, K.V. Roberts
Program title: OLYMPUS
Catalogue identifier: ABUF_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 7(1974)245
Programming language: Fortran.
Computer: ICL 4-70.
Operating system: ICL MULTIJOB.
RAM: 14K words
Word size: 32
Keywords: General purpose, Programming practice, Control, Utility, Package, Initial-value problems, Simulation, Computation, Standard framework, Kernel.
Classification: 4.14, 20.

Nature of problem:
A standard methodology has been established for constructing, testing and operating Fortran programs which solve equations describing initial-value problems. Such programs inevitably have many similair administrative tasks to perform and can therefore be given a similar structure. By standardizing this structure and making it as independent as possible of the computer system one can speed up the construction of programs and also facilitate communication between programmers, users and different computational physics groups. OLYMPUS is a control and utility package which is used to support the development and operation of initial-value and other Fortran programs written at Culham, one of which, MEDUSA 1, is described in the following paper.

Solution method:
The OLYMPUS package consists of three parts: 1. A kernel called CRONUS which comprises a main program, a general- purpose control subroutine COTROL, and a number of other subroutines some of which are dummies. 2. A set of utility subprograms called CYCLOPS. 3. A set of test and demonstration subroutines and data files called MINOS, which are first used to establish the OLYMPUS package on a different computer system and later serve as skeletons or templates from which a 'real' program can be built up. CRONUS itself is a 'null' program whose underlying structure together with that of MINOS is reflected in every 'real' program which uses the OLYMPUS methodology.

Restrictions:
The OLYMPUS package can be adapted to run with minor changes on any computer system for which a Standard Fortran compiler is provided. Library facilities should preferably be available so that the user need not handle the components of the package directly, and the availability of NAMELIST (not part of Standard Fortran) is helpful but not essential. The version presented here as Catalogue Number ABUF uses channel numbers and control cards applicable to the ICL 4/70 Multijob Operating System used at Culham, and intending users may find it more convenient to employ the version to be described in Comp. Phys. Commun. 7(9174)237, which has been adapted for CDC 6500. Although specifically designed for initial-value problems, the OLYMPUS methodology has been found to work well for many other types of computer application.

Running time:
The time taken by the null program CRONUS to perform a single step is 1.11 s on the ICL 4/70 at Culham Laboratory. The two MINOS tests occupy 3.23 s and 3.64 s respectively. Negligible overheads are imposed on any real calculation.