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authorJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
committerJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
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+.TH FCHISQ 3M
+.SH NAME
+fchisq
+.SH DESCRIPTION
+function fchisq.f
+
+source
+ Bevington, page 194.
+
+purpose
+ evaluate reduced chi square for fit of data
+ fchisq = sum ((y-yfit)**2 / sigma**2) / nfree
+
+usage
+ result = fchisq (y, sigmay, npts, nfree, mode, yfit)
+
+description of parameters
+ y - array of data points
+ sigmay - array of standard deviations for data points
+ npts - number of data points
+ nfree - number of degrees of freedom
+ 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
+
+subroutines and function subprograms required
+ none