**RSICC CODE PACKAGE PSR-382**

**1. NAME AND TITLE**

PLOTnFIT.4TH: Code System for Data Plotting and Curve Fitting.

**2. CONTRIBUTORS**

Nuclear Regulatory Commission, Washington, DC, through the Energy, Science, Technology Software Center, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

BASIC (99.5%) and Assembler (0.5%); IBM PS/2 (P00382IBMPC00).

**4. NATURE OF PROBLEM SOLVED**

PLOTnFIT is used for plotting and analyzing data by fitting nth degree polynomials of basis functions to the data interactively and printing graphs of the data and the polynomial functions. It can be used to generate linear, semilog, and log-log graphs and can automatically scale the coordinate axes to suit the data. Multiple data sets may be plotted on a single graph. An auxiliary program, READ1ST, is included which produces an on-line summary of the information contained in the PLOTnFIT reference report.

**5. METHOD OF SOLUTION**

PLOTnFIT uses the least squares method to calculate the coefficients of nth-degree (up to 10th degree) polynomials of 11 selected basis functions such that each polynomial fits the data in a least squares sense. The procedure incorporated in the code uses a linear combination of orthogonal polynomials to avoid ill-conditioning and to perform the curve fitting task with single-precision arithmetic.

**6. RESTRICTIONS OR LIMITATIONS**

Maxima of 225 data points per job (or graph) including all data sets, 8 data sets (or tasks) per job (or graph).

**7. TYPICAL RUNNING TIME**

Typical running times range from 2 to 25 minutes depending on the amount and complexity of the data analyzed and the amount of printed output requested.

**8. COMPUTER HARDWARE REQUIREMENTS**

PLOTnFIT requires an IBM PC,XT,AT, or compatible computer with 256 Kbytes of memory, one flexible disk drive, a color monitor, and color monitor graphics adaptor, and an Epson or compatible printer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

No executables are included in the package. PLOTnFIT was developed for DOS3.x. The DOS BASICA.com and GRAPHICS.COM programs are required. GRAPHICS must be loaded prior to BASICA in order to produce printied copies of graphs displayed on the monitor screen. A printer must be connected and turned on because PLOTnFIT always produces some printed output. Sample problems were executed by NESC January 1990 on an IBM PS/2 Model 70 and an AT&T 6300. The package was not tested when it was transferred to RSICC and released in July 2001.

**10. REFERENCES**

a) included in documentation:

J.O. Schiffgens, "PLOTnFIT: A BASIC Program for Data Plotting and Curve Fitting, NUREG-1378 (October 1989) and Errata (February 22, 1990).

L. Eyberger, PLOTnFIT, NESC No. 1130.PC_B, "PLOTnFIT Edition B Flexible Disk Cartridge Description and NUREG-1378 Reference Report Errata, National Energy Software Center Note 90-49 (March 7, 1990).

b) background references:

Wm. G. Hood, "Polynomial Curve Fitter, Byte, Vol. 12, No. 6,pp. 155-160 (June 1987).

H. D. Young, "Statistical Treatment of Experimental Data, McGraw-Hill, New York, (1962).

W. H. Press, et al., "Numerical Recipes: The Art of Scientific Computing," Cambridge University Press, Cambridge, MA (1986).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents in 10.a and a DOS formatted diskette which contains the BASIC source code and sample problem data.

**12. DATE OF ABSTRACT**

July 2001.

** KEYWORD:** PLOTTING