The Automatic Curve Fit command will fit one of a list of functions to the selected region of a graph or table window.
To perform an automatic curve fit, highlight the region of interest
by clicking and dragging the mouse across the graph. Click the Curve
Fit button on
the toolbar or select it from the Analyze
Menu. If multiple columns have been
graphed,
choose the appropriate column from the list displayed in the pop-up box
(This box will not appear if only one set of data has been graphed).
A reduced version of the graph will appear in the Curve Fit dialog
box.
Select Automatic under Fit Type. Note: if
Automatic Fit
Type is disabled,
you need to make sure that "Allow Automatic Curve Fit" is enabled in
the Preferences dialog.
Select the
General Equation you wish to
examine, and click on Try Fit. (Coefficients
are automatically applied, but can be adjusted. In this case, the Fit
Type
will revert to Manual).
To examine other curve fit options, select the function and click on Try Fit. Click Done to close the dialog box and place the fitted curve on the main graph. A helper object containing the equation and fit coefficients of the fitted function will also be added to the graph.
Logger Pro chooses the best fit using a least-squares approach. The
Mean Square Error is the sum of the distance squared of the difference
between the fitted line and the data points, divided by the number of
data
points. The curve with the smallest Mean Square Error is the one
chosen.
A tutorial covering curve fitting is available. Select Open from the
File menu, then look in the Experiments folder to access it.
See Also: