Data Fitting



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Data Fitting

The data can be fitted to (10) by iteratively using a standard least squares procedure. Care is required with the non-linear parameter . The quality of the fit can be tested by computing defined as

 

where runs over all data points and is the error in point . After fitting should be approximately equal to the number of data points less the number of fitted parameters. Hence the value of provides a measure of the quality of the fit. In the results presented here the range of values of disorder round the critical value was chosen such that conforms to this condition. Then a large number of additional points was calculated inside this range. An important side effect of this procedure is that the apparently acceptable range of disorder around the fixed point gets narrower as the calculations become more accurate. It is therefore important to test whether any apparent change in the fitted exponent is due to this narrowing.

The values of the ideal and the fitted as well as the range considered are shown in table 1. Using and the widest range of disorder and for rectangular and Gaussian cases respectively.



Angus MacKinnon - Aonghas Mac Fhionghuin
Tue Nov 29 13:32:02 gmt 1994