I need the algorithm behind polyfit function in Matlab

Hi, I need the algorithm behind polyfit function of matlab. I have a 3rd order polynomial curve. I need to find a polynomial best fit for the curve. kindly help me with the algorithm n procedure. Reply me to [e-mail]. Thank you.

Answer 1

[Walter Roberson]

http://www.mathworks.com/help/techdoc/ref/polyfit.html

Algorithms
The polyfit MATLAB file forms the Vandermonde matrix, V, whose elements are powers of x. v(i,j) = x(i)^(n-j)

It then uses the backslash operator, \, to solve the least squares problem Vp≅y.

You can modify the MATLAB file to use other functions of x as the basis functions.