Algebraic Problem in writing the function for LSQNONLIN tool in the Optimization Toolbox

Question

Rohan Khadatkar 2012-5-11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/38050-algebraic-problem-in-writing-the-function-for-lsqnonlin-tool-in-the-optimization-toolbox

采纳的回答： Andrei Bobrov

Hello,

I am using lsqnonlin for fitting a non linear equation to the model

z=Ax+(B*log(y))+(C/y)+(D*x*log(1+y))

X matrix is 10x2 double matrix. 1st column contains values for x and 2nd column contains values for y.

x(1) and x(2) represent x and y respectively in the model.

The function definition to be used in lsqnonlin is as follows:

function F=myfun(x,X,Z) k=1:10; F=(x(1)*X(k,1))+(x(2)*log(X(k,2)))+(x(3)/X(k,2))+(x(4)*X(k,1)*log(1+X(k,2)))-Z(k); end

I have all the values for the X and the Z matrix.

The problem is that whenever I am trying to call the myfun function, the error which it shows is:

??? Error using ==> plus Matrix dimensions must agree.

Error in ==> myfun at 3 F=( x(1) * X(k,1) )+( x(2) * log(X(k,2) )+( x(3) / X(k,2) )+( x(4) * X(k,1) * log(1+X(k,2) ) ) - Z(k);

Please clear this up.

Thank you.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Andrei Bobrov 2012-5-11

may be try use 'lsqcurvefit'

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Andrei Bobrov 2012-5-11

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/38050-algebraic-problem-in-writing-the-function-for-lsqnonlin-tool-in-the-optimization-toolbox#answer_47462

在 MATLAB Online 中打开

use function lsqcurvefit

eg:

A = .5;
B = 4.1;
C = .6;
D = .6;
x = (.01:.01:1)';y = (.01:.01:1)';
z = A*x+(B*log(y))+(C./y)+(D*x.*log(1+y))+.1*rand(size(x));
%solution:
f = @(a,X) a(1) * X(:,1) + a(2) * log(X(:,2)) +  a(3) ./ X(:,2) + a(4) * X(:,1) .* log(1+X(:,2) );
abcd = lsqcurvefit(f,[0 0 0 0],[x y],z)