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Re: Problem of polyfit
From: |
Tetsuro KURITA |
Subject: |
Re: Problem of polyfit |
Date: |
Thu, 6 Oct 2005 19:34:51 +0900 |
p = inv(X'*X)*X'*y
= inv(X)*inv(X')*X'*y
= inv(X)*I*y
= inv(X)*y
= X \ y
wpolyfit does the same with weighting on y, except that it uses QR
decomposition to solve X \ y.
In generaly,
inv(a*b) \= inv(b)*inv(a)
If both of a and b are nonsingular matrixes, the following equation is
right.
inv(a*b) = inv(b)*inv(a)
Acutually, in some case, polyfit.m give bad result.
=======================================================
Tetsuro KURITA
E-mail: address@hidden
=======================================================
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- Problem of polyfit, Tetsuro KURITA, 2005/10/06
- Re: Problem of polyfit, Paul Kienzle, 2005/10/06
- Re: Problem of polyfit,
Tetsuro KURITA <=
- Re: Problem of polyfit, Paul Kienzle, 2005/10/06
- Re: Problem of polyfit, Tetsuro KURITA, 2005/10/06
- Re: Problem of polyfit, Dmitri A. Sergatskov, 2005/10/07
- Re: Problem of polyfit, Tetsuro KURITA, 2005/10/07
- Re: Problem of polyfit, Fredrik Lingvall, 2005/10/07
- Re: Problem of polyfit, Tetsuro KURITA, 2005/10/07
- Re: Problem of polyfit, Paul Kienzle, 2005/10/07
- Re: Problem of polyfit, Fredrik Lingvall, 2005/10/07
- Re: Problem of polyfit, Paul Kienzle, 2005/10/07
Re: Problem of polyfit, Fredrik Lingvall, 2005/10/06