.TH POLFIT 3M
.SH NAME
polfit
.SH DESCRIPTION
subroutine polfit.f 

source
  Bevington, pages 140-142.

purpose
  make least-squares fit to data with a polynomial curve
    y = a(1) + a(2)*x + a(3)*x**2 + a(3)*x**3 + . . .

usage 
  call polfit (x, y, sigmay, npts, nterms, mode, a, chisqr)

description of parameters
  x      - array of data points for independent variable
  y      - array of data points for dependent variable
  sigmay - array of standard deviations for y data points
  npts   - number of pairs of data points
  nterms - number of coefficients (degree of polynomial + 1)
  mode   - determines method of weighting least-squares fit
           +1 (instrumental) weight(i) = 1./sigmay(i)**2
            0 (no weighting) weight(i) = 1.
           -1 (statistical)  weight(i) = 1./y(i)
  a      - array of coefficients of polynomial
  chisqr - reduced chi square for fit 

subroutines and function subprograms required 
  determ (array, norder)
    evaluates the determinant of a symetrical
      two-dimension matrix of order norder

comments
  valid for nterms up to 10