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Looking for a way to identify the peak in an XY Scatter Line Graph

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    Looking for a way to identify the peak in an XY Scatter Line Graph

    For my work i am required to complete some wet density calculations. I decided to make this easier on myself and drew up an excel spreadsheet to run the calculations and output a graph in the form that i need. The overall value i actually need from this graph is one that isn't part of the initial data series, so i cannot just hover over a point to get the data.

    I took the liberty of uploading the workbook, and am image with the point i'm trying to find the data for (or the approximate point...I'm trying to find the Highest point on the top of the curve near the RED marker)
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    Forum Guru Andy Pope's Avatar
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    Re: Looking for a way to identify the peak in an XY Scatter Line Graph

    The is no easy way to get the curve as it is not a single formula

    You maybe able to get a result using Smooth_curve_bezier
    https://www.xlrotor.com/knowledge-ce...m-calculators/

    Any technical reason why you applied a smooth curve to the line?
    Cheers
    Andy
    www.andypope.info

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    Re: Looking for a way to identify the peak in an XY Scatter Line Graph

    There are too many inflection points in the curve for Excel to be using splines. If you have only 3 points, you should be able to fit a 2nd order polynomial to it exactly. Take the derivative formula of that polynomial and find x for which y = 0. Then feed that x into the original polynomial.

    I get the 2nd order polynomial y = -0.0242 x2 + 0.0649 x + 2.1912. The derivative equation is dy/dx = -0.0484 x + 0.0649, and that has zero at x = 0.0649 / 0.0484 = 1.341. Plugging that into the original polynomial gives 2.235 to 3 decimal places/4 significant digits, which 3 data points don't really deserve. Nevertheless, that looks pretty close in terms of y value, even if it's a significantly smaller x value than you show in your sample chart.

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