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Diffstat (limited to 'math/bevington/man/legfit.3m')
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diff --git a/math/bevington/man/legfit.3m b/math/bevington/man/legfit.3m new file mode 100644 index 00000000..efe61c07 --- /dev/null +++ b/math/bevington/man/legfit.3m @@ -0,0 +1,49 @@ +.TH LEGFIT 3M +.SH NAME +legfit +.SH DESCRIPTION +subroutine legfit.f + +source + Bevington, pages 155-157. + +purpose + make least-squares fit to data with a Legendre polynomial + y = a(1) + a(2)*x + a(3)*(3x**2-1)/2 + ... + = a(1) * (1. + b(2)*x + b(3)*(3x**2-1)/2 + ... ) + where x = cos(theta) + +usage + call legfit (theta, y, sigmay, npts, norder, neven, mode, + ftest, yfit, a, sigmaa, b, sigmab, chisqr) + +description of parameters + theta - array of angles (in degrees) of the data points + y - array of data points for dependent variable + sigmay - array of standard deivations for y data points + npts - number of pairs of data points + norder - highest order of polynomial (number of terms - 1) + neven - determines odd or even character of polynomial + +1 fits only to even terms + 0 fits to all terms + -1 fits only to odd terms (plus constant term) + mode - determines mode 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) + ftest - array of values of f(l) for an f test + yfit - array of calculated values of y + a - array of coefficients of polynomial + sigmaa - array of standard deviations for coefficients + b - array of normalized relative coefficients + sigmab - array of std. deviations of relative coefficients + chisqr - reduced chi square for fit + +subroutines and function subprograms required + matinv (array, nterms, det) + inverts symmetric two-dimension matrix of degree nterms + and calculates its determinant + +comments + valid for npts up to 100 and order up to 9 + one source line modified - cos substituted for dcos |