The Microsoft Excel LINEST function is very useful when finding the Polynomial formula y = b + m1x + m2x^2 + m3x^3 + m4x^4 for a curve but the help information in Excel is a little difficult to understand. This description should make it a bit easier.
This function will only work in some versions of Microsoft Office if the appropriate Add-in has been installed. This can be verified by checking in the Excel toolbar:- Tools, Add-Ins, Analysis ToolPak.
Two columns of data are made containing the known X and Y coordinates of the curve. An example of this can be found at lin-spreadsheet-01.xls where the X and Y columns represent the Signal Generator Output ( Volts) and the DMM Reading ( Volts) of a non linear detector circuit respectively.
To demonstrate the use of the LINEST function copy the whole table(A1:A13,B1:B13) into a new spreadsheet.
Highlight the five cells (B17:F17) that are to contain the results and press F2 to select all five cells.
Enter the formula "=LINEST(A2:A13,B2:B13^{1,2,3,4})"
Press the CTRL + SHIFT + ENTER keys all together and the final calculation will be made.
An alternative method is given for the LOGEST function at Logest Function
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