Curve Fitting

Fit curves and surfaces to data

Description

The Curve Fitting app provides a flexible interface where you can interactively fit curves and surfaces to data and view plots.

You can:

• Create, plot, and compare multiple fits.

• Use linear or nonlinear regression, interpolation, smoothing, and custom equations.

• View goodness-of-fit statistics, display confidence intervals and residuals, remove outliers and assess fits with validation data.

• Automatically generate code to fit and plot curves and surfaces, or export fits to the workspace for further analysis.

Open the Curve Fitting App

• MATLAB® Toolstrip: On the Apps tab, under Math, Statistics and Optimization, click the app icon.

• MATLAB command prompt: Enter cftool.

Programmatic Use

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cftool opens Curve Fitting app or brings focus to the app if it is already open.

cftool( x, y ) creates a curve fit to x input and y output. x and y must be numeric, have two or more elements, and have the same number of elements. cftool opens Curve Fitting app if necessary.

cftool( x, y, z ) creates a surface fit to x and y inputs and z output. x, y, and z must be numeric, have two or more elements, and have compatible sizes. Sizes are compatible if x, y, and z all have the same number of elements or x and y are vectors, z is a 2D matrix, length(x ) = n, and length(y) = m where [m,n] = size(z). cftool opens Curve Fitting app if necessary.

cftool( x, y, [], w ) creates a curve fit with weights w. w must be numeric and have the same number of elements as x and y.

cftool( x, y, z, w ) creates a surface fit with weights w. w must be numeric and have the same number of elements as z.

cftool( filename ) loads the Curve Fitting session in filename into Curve Fitting app. The filename must have the extension .sfit.