Help with Excel 2007 curve interpolation

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Hi all,

Would be very grateful for any thoughts on this one. I've had a look at a lot of forum posts sites (here and elsewhere) but cannot quite find what I'm looking for. Just for background info, am trying to put together a spreadsheet for ship stability calculations.

Am not sure whether it is possible to do this with excel - would really appreciate your feedback.

1) I need to interpolate to find the maximum point of a curve on the Y axis, and the position of that point on the X axis. I can check the maximum data point easily, but how can I get the highest value of the curve when it is between two data points - as it almost always will be in my graph (looks similar to a bell curve)?

2) I need to draw a line tangental to the first part of the curve (say the first two points '0' and '5' below) and determine where it would intercept a line drawn vertically on the X axis. The value on the X axis I need is 1 radian (57.3 is close enough).

My X axis values will always be the same, the Y values will change as input conditions change.

An example set of values is below if that helps anybody.

X Y
0 0.000
5 0.155
10 0.319
15 0.487
20 0.649
25 0.766
30 0.879
35 0.968
40 1.019
45 1.020
50 0.966
70 0.384
90 -0.423

Again, would really appreciate any advice - even if it just that this isn't possible!

Very many thanks,

Cian
 
Hi Cian,

Did you ever find a solution for this in Excel. ?

I am now trying to do the same thing with a GZ curve.

Thanks, and have a great day

David
 
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