Plot a Point on the Curve at a Distance expressed in Percent of Length

I am trying to plot a point on a curve. The curve is specified with x,y data. I had some success calculating the length of the curve.

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My requirement is to plot a point on this curve at a percent length of the curved line. But still struggling to plot the point at a specified percentage of length at Cell:C17. Please assist.

Not sure what your question is. The formula you describe seems to be correct, if the goal is to find the point that is 45% of the distance along the final line segment. I am guessing that you are posing the question because you want something other than the 45% point along the final line segment. I am guessing that you want the 45% point along the full length of the curve (in this case, if I understood it correctly, I believe the correct answer for 45% should be (52.2, 1330)). Assuming I am understanding, here's an overview of how I would do this:

1) Add a column that computes the length of each segment.
2) Add a second column that computes the running total length
3) Compute the desired 45% (or whatever%) distance of the overall length and use a lookup function (approximate match option) to find the segment associated with that distance.
4) Extract the x and y coordinates for the desired segment, figure out the length along that segment, and finally figure out the point representing the 45% overall position.

Am I understanding correctly? Which part of that kind of solution do you need help with?

I used a few helper columns and this formula to work out the x (a similar for the y) point

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but easier to see in the attached sspreadsheet

My question -- because I like to use helper columns: Why do you need to get rid of the columns? Even in the older version (your profile says you are using 2003), you have 250 columns. Using 2 helper columns is a pretty small portion of the available columns (if your profile is in error and you have a newer version, then you have 16000 columns to use). If you find them offensive, these helper columns can be hidden (Select the full columns -> right click -> hide).

I would also note that, if you did get rid of the helper columns, then each copy of the formula (assuming you need multiple copies of the formula), would need to recreate these arrays resulting in a lot of duplicated effort. This duplicated effort leads to slow, inefficient spreadsheets.

It could be my personal programming bias, but I see no advantage to trying to get rid of these helper columns, and lots of advantages to keeping them. Hide them, if you don't want to look at them, but I would not try to eliminate them.

I’m with MrShorty on this. There seems to be a fixation on completing multiple calculations in one formula. While it may be a great achievement to do so I find it difficult to follow if i’ve Got to make changes at a later stage. Having helper columns helps debug and can give you an overview of what’s happening at a glance. You can hide them move them to the far right of the sheet or even put then on other tabs if you don’t like looking at them.