Solving an equation with symbolic matrix

5 次查看（过去 30 天）

显示更早的评论

Juan Ignacio Peña 2024-2-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2084373-solving-an-equation-with-symbolic-matrix

编辑： Torsten 2024-2-20

在 MATLAB Online 中打开

I've tried solving eq1 in the following program.

The right answer is w = -D*lambda*unos

%start

unos=ones(2,1)

unos = 2×1

1 1

ceros=zeros(2,1)

ceros = 2×1

0 0

E = symmatrix('E',2)

E =

D=inv(E)

D =

w=symmatrix('w',[2,1])

w =

eq1= w + D*lambda*unos==ceros

Unrecognized function or variable 'lambda'.

solve(eq1,w)

%end

The right answer is w = -D*lambda*unos

But instead, I get the following message:

Check for incorrect argument data type or missing argument in call to function 'solve'.

Please help

回答（1 个）

Torsten 2024-2-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2084373-solving-an-equation-with-symbolic-matrix#answer_1412693

https://uk.mathworks.com/matlabcentral/answers/1918100-error-using-solve-with-symmatrix-equation

Thank you, Torsten. I am interested in working with matrices as whole variables. I mean, considering matrices or vectors of generic size and with given assumptions (like symmetric, positive definite, etc), but without knowing the exact dimensions and elements. In my example, D is the inverse of a symmetric matrix, and I'm looking for the answer in terms of the matrix and not its elements.

As far as I understand, symmatrix2sym(D) converts a symbolic matrix variable D to an array of symbolic scalar variables S. I'm not interested in the elements of D. I am interested in working with D as a specific variable (of any dimension).