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Manuscript Title: Parameter search subroutine.
Authors: W.R. Smith
Program title: SEARCH
Catalogue identifier: ABOD_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 1(1969)135
Programming language: Fortran.
Computer: IBM 360/44.
Operating system: 44PS.
RAM: 1K words
Word size: 32
Keywords: General purpose, Parameter Optimization, Least-squares, Root-mean-square Minimization, Curve Fitting.
Classification: 4.9.

Revision history:
Type Tit le Reference
adaptation 0001 ADAPT SEARCH TO ELASTIC See below

Nature of problem:
Many computational problems require several parameters to be adjusted so that agreement with certain data is obtained. The subroutine SEARCH does this job automatically and can be adapted for use with any program with a minimum of difficulty.

Solution method:
The subroutine finds for each parameter the parameter value which causes the derivative, with respect to the parameter, of the root-mean-square deviation between data and calculation to vanish. Employing the method developed by Maddison, this minimization is carried out by means of a first order Taylor series expansion of the calculated results about some initial set of parameter values and replacement of derivatives at the minimizing parameter values with derivatives at the initial parameter values. The result is a set of simultaneous equations to be solved for the differences between the initial parameter values and the best-fit parameter values. If the predicted shift in any parameter is greater than 10%, then a step-wise search along the predicted parameter gradient is performed.

As set up, a maximum of 20 parameters and 200 data points can be simultaneously treated. However, these numbers can be arbitrarily increased or decreased by changing the dimensions of variables, so that the size restrictions essentially depend only on the computer storage available.

Running time:
The test case requires 88 seconds to compile and 6 seconds to run on the IBM 360 computer at Trinity University.

Manuscript Title: Adaptation of subroutine SEARCH for use with program ELASTIC.
Authors: W.R. Smith
Program title: 0001 ADAPT SEARCH TO ELASTIC
Catalogue identifier: ABOD_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 1(1970)198
Programming language: Fortran.
Classification: 4.9.