1. 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.

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

4. Thanks Steve I'll get them to check it out.

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

Andrew

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