NESC1130 PLOTNFIT.4TH.

1. NAME OR DESIGNATION OF PROGRAM:  PLOTnFIT.4TH.

3. DESCRIPTION OF PROGRAM OR FUNCTION

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 automayically 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.

4. 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 "i11-conditioning" and to perform the curve fitting task with  single-precision arithmetic.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

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

6. 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.

7. UNUSUAL FEATURES OF THE PROGRAM

PLOTnFIT is used to fit models (i.e. curves) to inexact data (i.e. data subject to measurements errors). It allows for modeling flexibility and the incorporation of data uncertainties, and yields model parameters and a statistical measure of goodness-of-fit.
In applications where there are no uncertainties in the data and the curve must pass exactly through the data points, methods (e.g.,  spline functions) other than those incorporated in PLOTnFIT should be used.

8. RELATED AND AUXILIARY PROGRAMS

This is the fourth and latest release in the PLOTnFIT family of programs.

10. REFERENCES

- William G. Hood:
  Polynomial Curve Fitter
  Byte, Vol. 12, No. 6, pp. 155-160 (June 1987).
- Hugh D. Young:
  Statistical Treatment of Experimental Data
  McGraw-Hill, New York (1962).
- William H. Press et al.:
  Numerical Recipes - The Art of Scientific Computing
  Cambridge University Press, Cambridge, MA (1986).

- J.O. Schiffgens:
  PLOTnFIT - A BASIC Program for Data Plotting and Curve Fitting
  NUREG-1378 (October 1989).
- ERRATA SHEET:
  NUREG-1378 (February 22, 1990).
- L. Eyberger:
  PLOTnFIT Flexible Disk Cartridge Description
  NESC Note 90-49 (March 7, 1990).

11. MACHINE 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. A math coprocessor is recommended, but  not required. PLOTnFIT may not run properly on a PC with a monochrome monitor. NESC executed PLOTnFIT successfully on an AT&T6300 with a monochrome monitor and CGA graphics adaptor.

IBM PC/AT with EGA color screen adapter and serial printer.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  DOS 3.x.

MS-DOS 3.20 with BASICA or GW-BASIC interpreter.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

PLOTnFIT requires the DOS BASICA.COM and GRAPHICS.COM programs. GRAPHICS must be loaded prior to BASICA in order to produce printed  copies of graphs displayed on the monitor screen. The computer must  be connected to a printer, with the printer on, when PLOTnFIT.4TH is operating; a PLOTnFIT job always produces some printed output.

15. NAME AND ESTABLISHMENT OF AUTHORS

         J.O. Schiffgens
         U.S. Nuclear Regulatory Commission

File name	File description	Records
NESC1130_01.001	NEA DATA BANK information file	72
NESC1130_01.002	BASICA source program	0
NESC1130_01.003	Sample problem part 1	19
NESC1130_01.004	Sample problem part 2	19
NESC1130_01.005	User primer to PLOTNFIT	0
NESC1130_01.006	DOS file-names	5