Re: polyfit: add the ability to specify the polynomial template

[Ben Abbott]

On Feb 4, 2012, at 9:51 AM, CdeMills wrote:

> Hello,
> 
> I enclose a patch against the stable branch polyfit.m in order to specify
> the polynomial template, i.e. giving the ability to force some of the
> coefficients to be zero. This is accomplished by passing a logical vector
> instead of a scalar for the last argument. Also compute C, the inverse of
> r.'*r, which is the unscaled covariance matrix. To obtain the standard
> deviation, simply take sqrt(diag(C)/df)*normr; where df are the degrees of
> freedom and normr the residual norm.
> 
> Changelog entry:
> 
> polyfit.m: add the ability to specify polynomial template
> 
> 
> Regards
> 
> Pascal
> 
> http://octave.1599824.n4.nabble.com/file/n4357144/polyfit.pat polyfit.pat 

I like your idea. I've been thinking of adding weights to polyfit as well. I 
haven't started on it, but I think the important part is embodied in one line.

-       p = r \ (q' * y);
+       p = (r \ (q' * (w .* y)));

My work on this isn't at the top of my list. If you're inclined to add this as 
well, please do.

Ben