Data from the curve of a chart

  • Thread starter Thread starter Dave Young
  • Start date Start date
D

Dave Young

I have a basic chart fusing the following data
1:52 3.58
7:24 2.35
13:58 3.89
20:46 1.91
2:58 3.79
8:51 2.15
15:00 4.12
21:44 1.57
3:50 4.09
9:51 1.82
15:52 4.41
22:31 1.22
I put this in as a line chart then smooth the lines to
give me a nice smooth chart. I was wondering if the Excel
chart can then give me the x & y values of points on the
curve in between the data values above. I used to have a
casio programable calculator that had a trace function on
it that could do exactly this where the cursor followed
the curve and provided an x value with a corresponding y
value - but it got stolen.

Very gratefull of any suggestions - Dave
 
It seems the calculator solution worked. If so, get another one. It's
probably the easiest solution since XL's smooth line algorithm is not
published. If you want to do this in XL, check the google.com archive
of the XL newsgroups. You'll find code from Dave Braden that comes
close to tracking the curve that XL uses, but it is not an exact match
near the end points.

If you want to use a simpler piecewise linear model, check the
'Interactive Chart' add-in available from my web site.

Like I wrote, it might be the easiest to get another calculator.

--
Regards,

Tushar Mehta, MS MVP -- Excel
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions
 
Brian Murphy has reverse engineered the bezier curve approach that Excel
seems to implement. He's posted a sample workbook on his web site which
I think will do what Dave asks. Brian's web site is:

http://xlrotor.com

- Jon
 
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