Your discussion of LINEST (LOGEST behaves similarly) explicitly continues the
misconception, fostered by Excel's Help, that LINEST is limited to simple
linear regression.  Actually the x data can be a rectangular region, in which
case LINEST does multiple regression linear in the unknowns.  Polynomial
regression is a special case that can be handled by array formulas without
the need to have the power columns explicitly exist on the worksheet, as in
 =LINEST(ycolumn,xcolumn^{1,2,3,...},intercept,stats)

The ATP regression tool simply reformats and expands (not always
intelligently) the output of LINEST.

Prior to 2003, LINEST could get into numerical difficulty quickly on
polynomial regressions that the chart trendline handled quite well.

"Improvements" to charting in 2007 make it unreliable in many instances that
LINEST now handles easily.

Jerry

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