[Matplotlib-users] polyfit implementation

[Jean-Michel P. <jea...@ar...>]

Hi,

I'm having some troubles while fitting data with high order polynomials 
(typically order 6). I looked at the polyfit function in 
'matplotlib/mlab.py' and I must say I don't understand why the 
least-square problem isn't solved using the matrix multiplication 
instead of the * multiplication. Unless I misunderstood something, 
shouldn't the following line:


c = array(linear_algebra.inverse(Xt*X)*Xt*y)  # convert back to array


be rewritten like this?


c = array(matrixmultiply(matrixmultiply( 
linear_algebra.inverse(matrixmultiply(Xt,X)), Xt), y) )  # convert back 
to array


Thanks.


JM. Philippe