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Title: COMP: a basic non-linear last squares curve fitting package. [Interactive program for PDP-11/34 or 11/70]

Abstract

To find a mathematical model which describes (fits) data from a process which is fundamentally nonlinear, one usually uses nonlinear least-squares techniques on maxicomputers. These usually run in batch mode with the user supplying a model and initial ''guesstimates'' of its parameters. However, fitting the model to the data can be considered an art because computer algorithms either converge to true solutions, or converge to erroneous solutions, or fail to converge, depending on the quality of the guesstimates. It is slow and expensive to try enough runs to obtain a logical solution (unless one makes lucky initial guesses). An interactive BASIC procedure was developed which runs on either the PDP-11/34 under RT-11 or the PDP-11/70 under IAS. These programs help the investigator quickly fit the model to the data and statistically evaluate the differences between the two. The parameter estimates thus determined may then be used as guesstimates for the more precise maxicomputer codes. The key to the system is the re-enterant nature of the curve fitting routine (allowed only with a language such as INTERPRETED BASIC). The user supplies estimates of the parameters for the selected model (18 are currently available, and users can easily write their own). Themore » computer tries a few iterative refinements (by using Taylor series expansion of partial derivatives to obtain linearization) of the estimates in an attempt to minimize the deviations between the values predicted by the model and the observed data. The user can observe as the program executes whether the result is a logical solution. If not, he may stop the process, enter new guesstimates, and examine those results, try again, or select a new model.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Battelle Pacific Northwest Labs., Richland, WA (USA)
OSTI Identifier:
6720176
Report Number(s):
BNWL-SA-6473; CONF-771144-6
DOE Contract Number:  
EY-76-C-06-1830
Resource Type:
Conference
Resource Relation:
Conference: DECUS meeting, San Diego, CA, USA, 28 Nov 1977; Other Information: Portions of document are illegible
Country of Publication:
United States
Language:
English
Subject:
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; COMPUTER CODES; C CODES; LEAST SQUARE FIT; MATHEMATICAL MODELS; BASIC; NONLINEAR PROBLEMS; PDP COMPUTERS; SERIES EXPANSION; COMPUTERS; MAXIMUM-LIKELIHOOD FIT; NUMERICAL SOLUTION; PROGRAMMING LANGUAGES; 990200* - Mathematics & Computers

Citation Formats

Watson, C. R., Cochran, M. I., Thomas, J. M., and Eberhardt, L. L. COMP: a basic non-linear last squares curve fitting package. [Interactive program for PDP-11/34 or 11/70]. United States: N. p., 1977. Web.
Watson, C. R., Cochran, M. I., Thomas, J. M., & Eberhardt, L. L. COMP: a basic non-linear last squares curve fitting package. [Interactive program for PDP-11/34 or 11/70]. United States.
Watson, C. R., Cochran, M. I., Thomas, J. M., and Eberhardt, L. L. 1977. "COMP: a basic non-linear last squares curve fitting package. [Interactive program for PDP-11/34 or 11/70]". United States. https://www.osti.gov/servlets/purl/6720176.
@article{osti_6720176,
title = {COMP: a basic non-linear last squares curve fitting package. [Interactive program for PDP-11/34 or 11/70]},
author = {Watson, C. R. and Cochran, M. I. and Thomas, J. M. and Eberhardt, L. L},
abstractNote = {To find a mathematical model which describes (fits) data from a process which is fundamentally nonlinear, one usually uses nonlinear least-squares techniques on maxicomputers. These usually run in batch mode with the user supplying a model and initial ''guesstimates'' of its parameters. However, fitting the model to the data can be considered an art because computer algorithms either converge to true solutions, or converge to erroneous solutions, or fail to converge, depending on the quality of the guesstimates. It is slow and expensive to try enough runs to obtain a logical solution (unless one makes lucky initial guesses). An interactive BASIC procedure was developed which runs on either the PDP-11/34 under RT-11 or the PDP-11/70 under IAS. These programs help the investigator quickly fit the model to the data and statistically evaluate the differences between the two. The parameter estimates thus determined may then be used as guesstimates for the more precise maxicomputer codes. The key to the system is the re-enterant nature of the curve fitting routine (allowed only with a language such as INTERPRETED BASIC). The user supplies estimates of the parameters for the selected model (18 are currently available, and users can easily write their own). The computer tries a few iterative refinements (by using Taylor series expansion of partial derivatives to obtain linearization) of the estimates in an attempt to minimize the deviations between the values predicted by the model and the observed data. The user can observe as the program executes whether the result is a logical solution. If not, he may stop the process, enter new guesstimates, and examine those results, try again, or select a new model.},
doi = {},
url = {https://www.osti.gov/biblio/6720176}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 1977},
month = {Tue Nov 01 00:00:00 EST 1977}
}

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