Name

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ROB_CHECKFIT

Purpose

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Used by ROBUST_... routines to determine the quality of a fit and to
return biweights.

Calling Sequence

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status = ROB_CHECKFIT( Y, YFIT, EPS, DEL, SIG, FRACDEV, NGOOD, W, B
BISQUARE_LIMIT = )

Input

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Y = the data
YFIT = the fit to the data
EPS = the "too small" limit
DEL = the "close enough" for the fractional median abs. deviations

Returns

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Integer status. if =1, the fit is considered to have converged

Outputs

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SIG = robust standard deviation analog
FRACDEV = the fractional median absolute deviation of the residuals
NGOOD = the number of input point given non-zero weight in the
calculation
W = the bisquare weights of Y
B = residuals scaled by sigma

Optional Input Keyword

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BISQUARE_LIMIT = allows changing the bisquare weight limit from
default 6.0

Procedures Used

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      ROBUST_SIGMA()

Revision History

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Written, H.T. Freudenreich, HSTX, 1/94