You could use LINEST (see my website) to find a polynomial of best fit and
then evaluate the differential of the equation at the point of interest
best wishes
--
Bernard V Liengme
www.stfx.ca/people/bliengme
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"Eutrapelia" wrote in message
...
Does anyone have a relatively precise method for calculating derivatives
in
Excel. There is of course the option of using the (A3-A1)/(B3-B1) to find
and approximation at B2, but does anyone have anything that is a bit more
reliable?

Thanks