Command for basic fitting

Hi,

I know we can use Tools -> Basic Fitting from the menu bar in the plot to generate linear or higher order equations for relationships between x and y. But it is a graphic way, if I want to draw the fitting curve by using m-script, which command should I use?

Thanks.

Y-L

Answer 1

[Grzegorz Knor]

To find the coefficients of a polynomial of degree n use polyfit function.

Alternatively use the option: File -> Generate M-file, to preview the source code.

[Yün Han]

Thanks. I know that polyfit could be used to calculate the coefficients of polynomials but what I want is after those coefficients are found out by polyfit, I want to use scripts to plot the fitting curve on the plot, just like using basic fitting. Any further ideas?

Answer 2

[UJJWAL]

Gregorz is right. Here is a bit of an example :

a= 1:0.1:10;
p = polyfit(a,exp(a),5); % Fits a fifth degree polynomial to exp(a) in the Least squares sense

v = polyval(p,a);

plot(a,v,a,exp(a)) % You will see the difference.

Happy To help

[Yün Han]

Thanks. polyval command is really what I want. :)