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  1. #1
    5 Star Lounger AndrewKKWalker's Avatar
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    This is a question from a colleague.
    They have a range of values and want to interpolate the values to a quadratic function.
    There are functions in Excel for Linear and Exponential interpolation,
    but is there anything for Quadratics other than using charts, pr writing a custom function.
    Andrew

  2. #2
    WS Lounge VIP sdckapr's Avatar
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    The LINEST function solves any linear equation (even quadratics). The general form it solves is:

    Y = A0 + A1*X1 + A2*X2 + A3*X3 + ... + Ak*Xk

    The line is
    Y = A0 + A1*X

    The simple quadratic is:
    Y = A0 + A1*X + A2*X^2

    The Cubic is:
    Y = A0 + A1*X + A2*X^2 + A3*X^3

    When you enter the ranges for the quadratic equation, you have a1 column range for the Y-values and a 2 column range for X: the first column contains the X values and the 2nd column contains the X^2 values....

    Steve

  3. #3
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    Here is an example of what Steve described: [attachment=86724:Quadratic.xls]

    Attached Files Attached Files

  4. #4
    5 Star Lounger AndrewKKWalker's Avatar
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    Thanks Steve I'll get them to check it out.


    And also Hans. I was writing the original reply as you were posting.

    Andrew
    Andrew

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