Least Square Method adaptation

Question

Erik 2014-4-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/126826-least-square-method-adaptation

回答： Niklas Nylén 2014-4-23

Hi i seem to have difficulties to understand how least square method works. I would appreciate if i could get help understanding what is wrong with this code, and suggestion on how to change it. I have tried to change it a lot of times but it never seem to work.

Note: its been a while since I have used matlab and it worked a year ago, som my guess is the language have changed.

thanks in advance.

function[A Deltapar] = MKA(x,y,deltay,n)

A = [];

Deltapar = [];

X=[];

%------------------------------------------------------------------------------------------------------------------ % checking if the size of the matrix is correct for indata

if (size(x,2)=1)

x=x';

endif

if (size(y,2)=1)

y=y';

endif

if(size(deltay,2)=1)

deltay=deltay';

endif

%------------------------------------------------------------------------------------------------------------------

% Checking if the matrix x and y and delta y have the correct size and after that executing least square method adaptation f

if(size(x)(2)==1 && size(y)(2) ==1 && size(deltay)(2)==1)

%------------------------------------------------------------------------------------------------------------------ % Conducting weighted least squares fit on the matrices x and y have the same format.

% If not, a message is returned back an x and y are not the same length.

if(length(x)==length(y))

for i=0:n

X=[X x.^i];

endfor

sigma=deltay;

vminus1 = diag(1./sigma.^2);

A = inv(X' * vminus1 * X) * (X' * vminus1 * y);

DeltaA = inv(X' * vminus1 * X);

Deltapar = sqrt(diag(DeltaA));

endif

disp('x,y har inte samma langd');

end %------------------------------------------------------------------------------------------------------------------ % Print "you did not write the input data on the correct form"

endif disp('you have not written the input data on the correct form'); end