How to solve these type of equation using matlab ?

Question

Harish kumar Kotapally 2014-9-8

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/153985-how-to-solve-these-type-of-equation-using-matlab

评论： Harish kumar Kotapally 2014-9-8

x*A+C*x*B=D where "x" is unknown vector of size(3*1) And A is of size(1*3) C is a matrix (3*3) B is again a vector of size (1*3) D is a matrix (3*3)

I used fsolve and lsqnonlin to solve this but unable to solve

A=[1 2 3] B=[4 5 6] C=[4 6 7 ; 8 3 4; 5 2 1] D=[4 2 1 ; 1 3 8; 5 2 1]

When i used fsolve

*Warning: Trust-region-dogleg algorithm of FSOLVE cannot handle non-square systems; using Levenberg-Marquardt algorithm instead. > In fsolve at 324

No solution found.

fsolve stopped because the problem appears regular as measured by the gradient, but the vector of function values is not near zero as measured by the default value of the function tolerance.

criteria details

x =

    0.1013
    0.0709
   -0.0630*

when i used lsqnonlin

*Local minimum found.

Optimization completed because the size of the gradient is less than the default value of the function tolerance.

criteria details

x =

    0.1013
    0.0709
   -0.0630*

But answer "x" is not satisfying the original equation. Please help me ! Thanks in advance.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Alan Weiss 2014-9-8

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/153985-how-to-solve-these-type-of-equation-using-matlab#answer_151037

In general I don't think that you can solve this kind of problem, because you have just 3 unknowns but you have 9 equations (one for each entry in D). So you would have to be lucky to be given a problem that is solvable.

I have not checked whether this particular problem is solvable, so you might be lucky. If you write out your 9 equations, you can try using backslash (also called mldivide) to solve them directly.

Alan Weiss

MATLAB mathematical toolbox documentation