# Differences

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 background_polynomial [2011/08/25 07:31]alancoelho background_polynomial [2011/08/25 19:12]alancoelho Both sides previous revision Previous revision 2015/06/16 13:20 alancoelho 2011/08/25 19:12 alancoelho 2011/08/25 07:36 alancoelho 2011/08/25 07:31 alancoelho 2011/08/25 07:28 alancoelho 2011/01/07 14:20 johnsoevans created Next revision Previous revision 2015/06/16 13:20 alancoelho 2011/08/25 19:12 alancoelho 2011/08/25 07:36 alancoelho 2011/08/25 07:31 alancoelho 2011/08/25 07:28 alancoelho 2011/01/07 14:20 johnsoevans created Next revision Both sides next revision Line 3: Line 3: Chebyshev polynomials of the first kind as described at http://​mathworld.wolfram.com/​ChebyshevPolynomialoftheFirstKind.html is used by default in Topas. The recurrences relations of Eq. (26) can be used with the x axis normalized to be between -1 and 1. Chebyshev polynomials of the first kind as described at http://​mathworld.wolfram.com/​ChebyshevPolynomialoftheFirstKind.html is used by default in Topas. The recurrences relations of Eq. (26) can be used with the x axis normalized to be between -1 and 1. - A Chebychev Polynomial, say order 5, written as a fit_obj ​can be coded as: + A Chebychev Polynomial, say order 5, written as: + + ​bkg @  359.793901` ​ 140.27403` ​ 67.3210027` ​ 21.057843` ​ 11.3443248` -4.46398819`​ + + can be coded as a fit_obj as follows: ​prm c0  359.79390` ​prm c0  359.79390` Line 33: Line 37: Note that X1 and X2 are reserved parameter names that correspond to the start and end of the x-axis. Note that X1 and X2 are reserved parameter names that correspond to the start and end of the x-axis. - The attached AAC.INP and data file demonstrates that the fit_obj coefficients after refinement corresponds exactly to those of the bkg Chebychev Polynomial. + --- //[[alan.coelho@bigpond.com|Alan Coelho]] 2011/08/25 19:12//