EzyFit Getting Started |

The EzyFit toolbox for Matlab enables you to perform simple curve fitting of one-dimensional data using arbitrary fitting functions. It provides command-line functions and a basic graphical user interface for interactive selection of the data.

There are three ways to perform curve fitting with Matlab: the first
one is using the 'Basic Fitting Interface' of Matlab, the second one is using
`fminsearch` with anonymous functions, and the third one
is to pay for the
Curve Fitting Toolbox.
However, for usual curve fitting of 1D data, you may find the first solution
rather limited, the second one a little complicated, and the third one quite
expensive...

The EzyFit Toolbox provides a free, simple and efficient way to
perform quick curve fitting with arbitrary (nonlinear) fitting functions:
You just have to type something like `showfit('c+a/x^n')` and EzyFit gives
you the values for `c`, `a` and `n` and shows you the
curve! EzyFit also provides a basic graphical user interface
to interactively fit selected parts of your data.

First plot some sample data by typing
`plotsample`
in the command window (or simply click here
to display the sample figure).

In the `EzyFit` menu of the figure window, select `Showfit`
and
choose an appropriate fitting function to fit the sample data. You may also click
on the link that appears in the command window to choose the default
fitting function associated to the sample plot. If the menu is not present in
your figure window, type `efmenu`,
or see the step 4 in the installation procedure.

Choose `Undo Fit` if you want to remove the fit.

If multiple curves are present in the figure,
first select the one you want to fit, and then choose `Showfit`.

Two additional functions, `getslope` and
`showslope`, return the slope of the selected
line (use the menu
`Insert > Line`), or drag a line of fixed slope, for a fit "by eye"
of your data.

Although fitting your data from the `EzyFit` menu is fast and easy,
using the command-line functions is much more powerful, and allows for
using different properties for each fit (See the Settings
page for details).

The key function of the toolbox is `ezfit`,
which computes the coefficients that fit the data. The function
`showfit` simply calls the function
`ezfit` for the active curve, using the
"Data Brushing" tool of Matlab (available since version 7.6).
Type undofit to remove the last fit.

This example fits some noisy data by a power law `c * x^n` and plots the result:

plotsample power % a power law showfit c*x^n

This example fits an histogram with a Gaussian, and displays the coefficients in the Array Editor:

plotsample hist % an histogram f = ezfit('gauss'); % fits with a Gaussian f % displays the fit structure showfit(f); % displays the fit editcoeff(f); % opens the Array Editor

Have a look to the Sample session for more examples.

See also the Frequently Asked Questions section and the Function by category section to learn more about this toolbox.

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