Analysis_Software

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9.2.3. Curve Fitting
KaleidaGraph allows various styles of curve fitting, including linear, polynomial, logarithmic, and
exponential. To fit the data in your plot, choose the type of fit you want from the Curve Fit menu. For
example, let’s fit the above data with a parabola; i.e. choose “polynomial” fit. A window opens up asking
which curve to fit (if you have multiple curves), then which degree of polynomial: choose 2nd degree for a
parabola. The result is (also including some cleaning up of axes):
6
sample KG data.txt
5
Position (cm)
4
3
2
1
Y = M0 + M1*x + ... M8*x 8 + M9*x 9
M0
0.25105499017
M1
2.0792304377
M2
2.8269760865
R
0.98539870081
0
0
0.2 0.4 0.6 0.8 1
Time (sec)
The box to the right shows the equation of the best-fit line and some curve fit statistics. If it doesn’t appear
when you do the fit, choose “Display Equation” from the Plot menu.
9.2.4. Multiple Curves
Plotting multiple curves is easy with KaleidaGraph. If your data file has three columns, for example,
and you want to plot columns 1 and 2 versus column 0, just choose c1 and c2 as the y-axis in the pop-up
window that appears when you choose your plot type.
If you want to plot data from different files on the same plot, open all the files simultaneously. Choose
the plot type as usual from the Gallery menu. The axis selection window then pops up and notice that the
box containing the file name for the top data file looks “3-Dimensional”, as if it has some thickness. This
is KaleidaGraph’s way of telling you that there is a pop-up menu under the box: click on it and hold the
mouse button down and you will see the names of all the open files. Select each one in turn and choose
which columns to put on the x and y axes. When you’re finished click “OK” and the plot will be made.
9.2.5. Formulas
To do computations with your data, use the formula window. If you can’t see it, choose “Formula
Entry” from the Windows menu. Type the formula you want to use in the window, e.g.:
c2 = c0^2 + exp(c1)
and click “OK”. Column 2 will be computed and added (or modified if it already exists) to the data
window. Check out the “Help” under the Apple menu to get a list of which functions KaleidaGraph knows.