AFAIK, MS has never published its smoothened curve algorithm. The
closest anyone has come to figuring it out is Brian Murphy with his
Bezier curve approximation. See the downloadable file at
http://xlrotor.com/resources/files.shtml

Dave Braden's cubic spline algorithm also comes close. Search the
google.com archive of the XL newsgroups.

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Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article ,
says...

Hi,
I have a set of data, 100 x-values with corresponding y-values. Only
about every third of the y's have a value, but by letting excel
interpolate the graph, I can see how the graph should look like.

My questions a
1. Can excel give me the formula to the graph it has drawn? Something
like: "Show Equation"?

2. Is there a way to find out the y-value to a corresponding x-value?
The graph has no standard-form, ie. it's not a parabel, so I don't know
if I can use "trend" or "forecast"? The form of the graph is highly
irregular, but excel managed to draw the graph, so it must know all
it's y-values?

Please ask if anything is badly explained.

Thanks, perolav


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perolav
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