Split Curves

[develaavi]

Hello all,
Iam student and for a lab test I need to solve about 450 excel sheets for my project.
The spreadsheet has X and Y data and curve is plotted. I need to split the curves into 3 parts based on major slope change and fit a trendline.
I can do it manually but I need an excel Macro which does this work. Iam trying for trendline with Rsquare >0.95 for all curves. How to do it with a vba, I want the idea. I can then write the code.

A sample is attached.

X Y

0	0
1	20
2	70
3	100
4	110
5	120
6	135
7	145
8	160
9	170
10	180
11	190
12	200
13	210
14	220
15	230
16	240
17	250
18	260
19	270
21	280
22	290
23	300
26	310
29	325
30	335
32	345
34	355
39	365
44	375
50	385
58	395
66	405
73	415
81	425
91	435

<colgroup><col><col></colgroup><tbody>
</tbody>

 

[shg]

If you use a 4th-order polynomial, R2 = 0.995

 

[develaavi]

If you use a 4th-order polynomial, R2 = 0.995

No sir,
These are different soil layers for which strengths are different. These strengths are found out using the slopes of trendlines eq.
So curves should be split based on rsquares of trendlines. I found by adding each xy point to check Rsquare value. When this values is less than 0.95, I decide this to be a single layer. I then start adding a new series ​and then follow the same.

 

[develaavi]

Split Curves

 

[develaavi]

Split a Curve - Vba Macro