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Thread Subject:
Regression, fitting

Subject: Regression, fitting

From: Baha

Date: 26 Sep, 2013 02:59:04

Message: 1 of 2

Hi all,
I got confused with this problem, please take a look.
I have these input:
x1 = 0:5:30;
x2 = 0:0.25:1;
Response values corresponding to (x1,x2) pairs:
% x2: \ x1: 0 5 10 15 20 25 30
% 0.00 -> [ 1.6 1.55 1.5 1.45 1.4 1.35 1.3 ]
% 0.25 -> [ - - - - - - - ]
% 0.50 -> [ - - - - - - - ]
% 0.75 -> [ - - - - - - - ]
% 1.00 -> [ - - - - - - - ]
% this matrix created below as Y
%
Y0 = linspace(1.6, 1.3, 7);
Y = repmat(Y0,5,1) + 0.05*randn(size(repmat(Y0,5,1))); % just add noise
%
% form of regression:
% Y = Y * [1 - 1/8000*(1-x2)^b1*(a1*x1^2+a2*x1+a3)];
% Four coeff's to be found: approx-> b1=1.2; a1=1; a2=-50; a3=-200;

Any help appreciated.
Thanks,
Baha

Subject: Regression, fitting

From: Baha

Date: 26 Sep, 2013 08:39:05

Message: 2 of 2

TYPO: In expression for Y, there is no Y but a constant Yo, so
Yo = 1.3;
Y = Yo * [1 - 1/8000*(1-x2)^b1*(a1*x1^2+a2*x1+a3)];

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