The LOGEST function in Excel is very useful when finding the formula for a curve but the help information in Excel is a little difficult difficult to understand. This description should make it a bit easier.
Two columns of data are made containing the known X and Y coordinates of the curve. An example of this can be found at Spreadsheet-01.xls where the X and Y columns represent the Signal Generator Output ( Volts) and the DVM Reading ( Volts) respectively. To understand the use of the LOGEST function copy the whole table(A4:A16,E4:E16) into a new spreadsheet.
Highlight the two cells that are to contain the results and select the LOGEST function from the toolbar at Insert/Function/Statistical/LOGEST and hit OK. The LOGEST box will appear and the cursor will be in the Known_y's box. Select the Signal Generator Output ( Volts ) column with mouse and the cell references will appear in the Known_y's box.
Left click the mouse in the Known_x's box and select the DVM Reading ( Volts) column with mouse and the cell references will appear in the Known_x's box.
Left click the mouse in the Const box and enter a 1 for the constant which will ensure that b in the formula y = b*m^x is used.
Left click the mouse in the Stats box and enter a 0 for the stats which will ensure that the regression statistics are not returned.
Hit OK and then the keyboard function key F2.
Press the CTRL + SHIFT + ENTER keys all together and the final calculation will be made.
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