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.TH REGRES 3M
.SH NAME
regres
.SH DESCRIPTION
subroutine regres.f
source
Bevington, pages 172-175.
purpose
make mulitple linear regression fit to data with specified
function which is linear in coefficients
usage
call regres (x, y, sigmay, npts, nterms, m, mode, yfit,
a0, a, sigma0, sigmaa, r, rmul, chisqr, ftest)
description of parameters
x - array of points for independent variable
y - array of points for dependent variable
sigmay - array of standard deviations for y data points
npts - number of pairs of data points
nterms - number of coefficients
m - array of inclusion/rejection criteria for fctn
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)
yfit - array of calculated values of y
a0 - constant term
a - array of coefficients
sigma0 - standard deviation of a0
sigmaa - array of standard deviations for coefficients
r - array of linear correlation coefficients
rmul - multiple linear correlation coefficient
chisqr - reduced chi square for fit
ftest - value of f for test of fit
subroutines and function subprograms required
fctn (x, i, j, m)
evaluates function for the jth term and the ith data
point using array m to specify terms in function
matinv (array, nterms, det)
inverts symmetric two-dimension matrix of degree nterms
and calculates its determinant
comments
valid for npts up to 100 and nterms up to 10
one source line modified - sigmaa substituted for sigmaag
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