MATLAB: Get the equation of the graph plotted into the workspace OR how the equation can be generated explicitly

MATLAB

I obtained the equation of a graph plotted using the Basic fitting option ( Plot the graph-> Tools–>Basic Fitting–>show equations). But, can some one explain how these equations are calculated( say, for a 3rd degree polynomial function)? Is there a code available for this? Any ideas is highly appreciated.

Best Answer

Let x and y be your data.
Use polyfit to fit coeffecients to your data using a third order polynomial.
P = polyfit(x, y, 3)
Evaluate the data at points xe
xe = ... 
ye = polyval(p, xe)
You can then plot xe and ye alongside your data.
If what you are really looking for is how the fitting is performed inside of polyfit, then read about least-square fitting
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