LINEST range based on value of Column

Hi Guys,

I'm currently doing a project at university and need to work out the coefficients of a 2nd order polynomial for the speed of a deceleration of a car.
I have some data from a logger which was recorded at a sample rate of 1 second.
I've fitted a Linest to this data, yet I have 65 cars of data to go through and thought making a macro would be the best way.

At the moment I do a lot of manual editing before I can even get to this stage of running the Linest.

The section of data which I use for the Linest, is determined by the clutch switch. The clutch switch value is contained in column C, when the clutch is engaged its 1 and disengaged is 0

What I currently do is, at the first clutch value of 1 I start a new column(D) and write numbers increasing from 1 until the next clutch value of 0.

Using the linest I use Column(D) as x values and vehicle speed - Column(A) as y.
The row number begins at the first clutch value of 1 and stops at next clutch value of 0.

I have attached an excel document with two tabs, the first showing the completed sheet with the extra column and the linest result, the second being the RAW data which I start with.

If anyone could help to show me what formulas to use and help me on my way I would really appreciate it.

Thanks

Hi

You may want to move the positions, but try this

D5: =IF(C5=0,0,D4+1). Copy down to cover all your data
G5: =MATCH(1,D:D,0)
H5: =MATCH(MAX(D:D),D:D,0)
G10:I10: =LINEST(INDIRECT("a" & G5 & ":A" & H5),INDIRECT("D" & G5 & ":D" & H5)^{1,2},,TRUE) (array entered)

HTH

rylo

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